Olav Sand

• Sand, Olav; Popper, Arthur N. & Hawkins, Anthony D. (2023). Evolution of the Understanding of Fish Hearing. In Ketten, Darlene R.; Coffin, Allison B.; Fay, Richard R. & Popper, Arthur N. (Ed.), A History of Discoveries on Hearing. Springer Nature. ISSN 9783031413193. p. 39–73. doi: 10.1007/978-3-031-41320-9_3. Full text in Research Archive
• Sand, Olav (2023). A journey through the field of fish hearing. Journal of the Acoustical Society of America. ISSN 0001-4966. 153(5), p. 2677–2689. doi: 10.1121/10.0017833. Full text in Research Archive Show summary

  My interest in fish bioacoustics was ignited more than 50 years ago and resulted in a zigzag time travel between various interesting problems that were unsettled at the time. The present paper gives a brief overview of the main topics I have worked on in the field of fish hearing, i.e., auditory function of the swim bladder, directional hearing, function of the lateral line system, and infrasound sensitivity. Rather than being a comprehensive review of these issues, the paper is autobiographical and limited. The aim is to show young scientists that experimental science can be exciting, diverse, and rewarding—and open doors to a rich collegial network, collaboration, and friendships.

• Popper, Arthur N.; Hawkins, Anthony D.; Sand, Olav & Sisneros, Joseph A. (2019). Examining the hearing abilities of fishes. Journal of the Acoustical Society of America. ISSN 0001-4966. 146(2), p. 948–955. doi: 10.1121/1.5120185. Full text in Research Archive
• Braun, Christopher B. & Sand, Olav (2014). Functional overlap and nonoverlap between lateral line and auditory systems. In Coombs, Sheryl; Bleckmann, Horst; Fay, Richard R. & Popper, Arthur N. (Ed.), The Lateral Line System. Springer Science+Business Media B.V.. ISSN 9781461488507. p. 281–312. doi: 10.1007/978-1-4614-8851-4. Full text in Research Archive
• Sand, Sverre; Nissen-Meyer, Jon; Sand, Olav & Haug, Trude M (2013). Plantaricin A, a cationic peptide produced by Lactobacillus plantarum, permeabilizes eukaryotic cell membranes by a mechanism dependent on negative surface charge linked to glycosylated membrane proteins. Biochimica et Biophysica Acta - Biomembranes. ISSN 0005-2736. 1828(2), p. 249–259. doi: 10.1016/j.bbamem.2012.11.001. Full text in Research Archive
• Hodne, Kjetil; Strandabø, Rønnaug; Krogh, Kristine von; Nourizadeh-Lillabadi, Rasoul; Sand, Olav & Weltzien, Finn-Arne [Show all 7 contributors for this article] (2013). Electrophysiological differences between fshb- and lhb-expresing gonadotropes in primary culture. Endocrinology. ISSN 0013-7227. 154(9), p. 3319–3330. doi: 10.1210/en.2013-1164. Full text in Research Archive
• Grønlien, Heidi Kristine; Bruskeland, Guttorm Eric; Borgersen, Anne-Kari & Sand, Olav (2013). Electrophysiological Properties of the Microstome and Macrostome Morph of the Polymorphic Ciliate Tetrahymena vorax. Journal of Eukaryotic Microbiology. ISSN 1066-5234. 60(1), p. 57–69. doi: 10.1111/jeu.12006. Full text in Research Archive
• Strandabø, Rønnaug; Hodne, Kjetil; Ager-Wick, Eirill; Sand, Olav; Weltzien, Finn-Arne & Haug, Trude M (2013). Signal transduction involved in GnRH2-stimulation of identified LH-producing gonadotropes from lhb-GFP transgenic medaka (Oryzias latipes). Molecular and Cellular Endocrinology. ISSN 0303-7207. 372(1-2), p. 128–139. doi: 10.1016/j.mce.2013.03.022. Full text in Research Archive
• Hodne, Kjetil; Krogh, Kristine von; Weltzien, Finn-Arne; Sand, Olav & Haug, Trude M (2012). Optimized conditions for primary culture of pituitary cells from the Atlantic cod (Gadus morhua). The importance of osmolality, pCO(2), and pH. General and Comparative Endocrinology. ISSN 0016-6480. 178(2), p. 206–215. doi: 10.1016/j.ygcen.2012.06.005. Full text in Research Archive
• Grønlien, Heidi Kristine; Hagen, Bjarne & Sand, Olav (2011). Microstome-macrostome transformation in the polymorphic ciliate Tetrahymena vorax leads to mechanosensitivity associated with prey-capture behaviour. Journal of Experimental Biology. ISSN 0022-0949. 214, p. 2258–2266. doi: 10.1242/jeb.055897. Full text in Research Archive
• Andersland, Kristin; Jølle, Guro Five; Sand, Olav & Haug, Trude M (2010). Peptide Pheromone Plantaricin A Produced by Lactobacillus plantarum Permeabilizes Liver and Kidney Cells. Journal of Membrane Biology. ISSN 0022-2631. 235(2), p. 121–129. doi: 10.1007/s00232-010-9263-4. Full text in Research Archive
• Grønlien, Heidi Kristine; Rønnevig, Anna Kari; Hagen, Bjarne & Sand, Olav (2010). Chemo-accumulation without changes in membrane potential in the microstome form of the ciliate Tetrahymena vorax. Journal of Experimental Biology. ISSN 0022-0949. 213(23), p. 3980–3987. doi: 10.1242/jeb.042903. Full text in Research Archive Show summary

  The swimming behaviour of ciliates is mainly determined by membrane potential and transmembrane fluxes. In a chemical gradient, swimming ciliates may approach or move away from the source. Based on experiments on Paramecium, it is generally assumed that chemical attractants and repellents affect the swimming behaviour of ciliates by specific changes of the membrane potential. We have examined if there is causal relationship between membrane potential and chemo-accumulation in the microstome form of the polymorphic ciliate Tetrahymena vorax. Effects of chemo-attractants on the membrane potential of Tetrahymena have not previously been reported. Microstome T. vorax cells aggregate close to a point source of L-cysteine and the complex meat hydrolysate proteose peptone. Chemo-accumulated cells displayed a significantly higher turning frequency than control cells at a similar cell density. 20 mmol l-1 L-cysteine did not evoke any detectable change in the membrane potential, whereas 1% proteose peptone depolarized the cells about 12 mV. This is contrary to the current model, which predicts agents that induce a moderate depolarization to be repellents. A solution of 1% proteose peptone contains 21 mmol-1 Na+. A solution of 21 mmol-1 NaCl without organic compounds also caused approximately 12 mV depolarization, but had no aggregating effect on the cells. Collectively, the electrophysiological and behavioural data indicate that chemo-accumulation in the microstome form of T. vorax is not obligatory governed by the membrane potential. We thus suggest that the simple membrane potential model for chemokinesis in Paramecium may not be valid for T. vorax.

• Sand, Sverre; Oppegård, Camilla; Ohara, S.; Iijima, Toshio; Naderi, Soheil & Blomhoff, Heidi Kiil [Show all 8 contributors for this article] (2010). Plantaricin A, a peptide pheromone produced by Lactobacillus plantarum, permeabilizes the cell membrane of both normal and cancerous lymphocytes and neuronal cells. Peptides. ISSN 0196-9781. 31(7), p. 1237–1244. doi: 10.1016/j.peptides.2010.04.010. Full text in Research Archive
• Haug, Trude Marie; Sand, Sverre; Sand, Olav; Phung, Danh; Granum, Per Einar & Hardy, Simon P. (2010). Formation of Very Large Conductance Channels by Bacillus cereus Nhe in Vero and GH4 Cells Identifies NheA + B as the Inherent Pore-Forming Structure. Journal of Membrane Biology. ISSN 0022-2631. 237, p. 1–11. Full text in Research Archive
• Sun, Xiaoping; Chen, Bo-Ming; Sand, Olav; Kidokoro, Yoshi & Grinnell, Alan D. (2010). Depolarization-Induced Ca2+ Entry Preferentially Evokes Release of Large Quanta in the Developing Xenopus Neuromuscular Junction. Journal of Neurophysiology. ISSN 0022-3077. 104(5), p. 2730–2740. doi: 10.1152/jn.01041.2009. Full text in Research Archive
• Haug, Trude M; Sand, Sverre; Sand, Olav; Phung, Danh; Granum, Per Einar & Hardy, Simon P. (2010). Formation of Very Large Conductance Channels by Bacillus cereus Nhe in Vero and GH(4) Cells Identifies NheA plus B as the Inherent Pore-Forming Structure. Journal of Membrane Biology. ISSN 0022-2631. 237(1), p. 1–11. doi: 10.1007/s00232-010-9298-6. Full text in Research Archive
• Knudsen, Frank R.; Hawkins, Anthony D.; McAllen, Rob & Sand, Olav (2009). Diel interactions between sprat and mackerel in a marine lough and their effects upon acoustic measurements of fish abundance. Fisheries Research. ISSN 0165-7836. 100(2), p. 140–147. doi: 10.1016/j.fishres.2009.06.015. Full text in Research Archive Show summary

  We have investigated how diel changes in fish behaviour may affect acoustic estimates of fish abundance in a marine system. Studies in Lough Hyne (Ireland), a marine lake with only a narrow and shallow connection to the sea, showed the presence of large numbers of sprat (Sprattus sprattus), mackerel (Scomber scombrus), and zooplankton. Fish species were identified from regular rod and line fishing. Zooplankton were identified fromnet hauls. Acoustic measures of zooplankton were low with little diel variation. The sprat formed dense schools during the day and dispersed into the water column at night. The acoustic estimate of sprat abundance at night, obtained by means of a standard hydroacoustic technique and protocol, was more than double the estimated biomass during the day. We have considered whether the lower fish estimate during daytime resulted from acoustic shadowing due to aggregation of the fish into dense schools. However, no decrease in echo energywas evident fromthe top to the bottomof the schools, and there was no reduction in the seabed echo beneath the schools. Acoustic shadowing was therefore not responsible for the diel differences in the estimates of abundance. Instead, we suggest that the target strength of individual sprat diminished during the day as a result of attacks from predatory mackerel.We observed echoes from gas released by the sprat as they gathered into dense plumes close to the seabed. Compression of the gas remaining within the swim bladder as the fish were moving deeper would also reduce swim bladder volume. Finally, negative buoyancy due to reduced swim bladder volume may in addition have forced the fish to change tilt angle to compensate for sinking. All these effects will reduce the target strengths of individual fish and lead to underestimation of fish abundance based on daytime surveys.

• Sand, Olav & Bleckmann, Horst (2008). Orientation to auditory and lateral line stimuli. In Webb, Jacqueline F.; Popper, Arthur n. & Fay, Richard R. (Ed.), Fish Bioacoustics. Springer Science+Business Media B.V.. ISSN 9780387730288. p. 183–231. Full text in Research Archive
• Sand, Olav (2008). Detection of sound by fish: a minireview. Bioacoustics. ISSN 0952-4622. 17, p. 92–95. Full text in Research Archive
• Haug, Trude M; Hodne, Kjetil; Weltzien, Finn-Arne & Sand, Olav (2007). Electrophysiological properties of pituitary cells in primary culture from Atlantic cod (Gadus morhua). Neuroendocrinology. ISSN 0028-3835. 86, p. 38–47. doi: 10.1159/000103867. Full text in Research Archive
• Sand, Sverre; Haug, Trude M; Nissen-Meyer, Jon & Sand, Olav (2007). The bacterial peptide pheromone plantaricin a permeabilizes cancerous, but not normal, rat pituitary cells and differentiates between the outer and inner membrane leaflet. Journal of Membrane Biology. ISSN 0022-2631. 216(2-3), p. 61–71. doi: 10.1007/s00232-007-9030-3. Full text in Research Archive
• Sonny, Damien; Knudsen, Frank R.; Enger, Per Stockfleth; Kvernstuen, Torstein & Sand, Olav (2006). Reactions of cyprinids to infrasound in a lake and at the cooling water inlet of a nuclear power plant. Journal of Fish Biology. ISSN 0022-1112. 69, p. 735–748. Full text in Research Archive
• Hafting, Torkel; Haug, Trude M; Ellefsen, Stian & Sand, Olav (2006). Hypotonic stress activates BK channels in clonal kidney cells via purinergic receptors, presumably of the P2Y1 subtype. Acta Physiologica. ISSN 1748-1708. 188(1), p. 21–32. doi: 10.1111/j.1748-1716.2006.01601. Full text in Research Archive
• Mørk, Halvor Kjeang; Haug, Trude M & Sand, Olav (2005). Contribution of different Ca-activated K channels to the first phase of the response to TRH in clonal rat anterior pituitary cells. Acta Physiologica Scandinavica. ISSN 0001-6772. 184(2), p. 141–150. doi: 10.1111/j.1365-201X.2005.01441. Full text in Research Archive
• Haug, Trude M; Hafting, Torkel & Sand, Olav (2004). Inhibition of BK channels contributes to the second phase of the response to TRH in clonal rat anterior pituitary cells. Acta Physiologica Scandinavica. ISSN 0001-6772. 180, p. 347–357. Full text in Research Archive
• Karlsen, Hans Erik; Piddington, Robert W; Enger, Per Stockfleth & Sand, Olav (2004). Infrasound initiates directional fast-start escape responses in juvenile roach Rutilus rutilus. Journal of Experimental Biology. ISSN 0022-0949. 207, p. 4185–4193. Full text in Research Archive Show summary

  Acoustic stimuli within the sonic range are effective triggers of C-type escape behaviours in fish. We have previously shown that fish have an acute sensitivity to infrasound also, with thresholds in the range of 10-5 m/s2. In addition, infrasound at high intensities around 10-2 m/s2 elicits strong and sustained avoidance responses in several fish species. In the present study, the possible triggering of C-escapes by infrasonic single-cycle vibrations was examined in juvenile roach (Rutilus rutilus). The fish were accelerated in a controlled and quantifiable manner using a swing system. The applied stimuli simulated essential components of the accelerations a small fish would encounter in the hydrodynamic flow field produced by a predatory fish. Typical C- and S-type escape responses were induced by accelerations within the infrasonic range with a threshold of 0.023 m/s2 for an initial acceleration at 6.7 Hz. Response trajectories were on average in the same direction as the initial acceleration. Unexpectedly, startle behaviours mainly occurred in the trailing half of the test chamber, in which the fish were subjected to linear acceleration in combination with compression, i.e. the expected stimuli produced by an approaching predator. Very few responses were observed in the leading half of the test chamber, where the fish were subjected to acceleration and rarefaction, i.e. the stimuli expected from a suction type of predator. We conclude that particle acceleration is essential for the directionality of the startle response to infrasound, and that the response is triggered by the synergistic effects of acceleration and compression.

• Pettigrew, John D; Sand, Olav & Gynther, Ian (2004). Error rate of axons at the owl's potic chiasm. Clinical and experimental optometry. ISSN 0816-4622. 87(2), p. 93–96. Full text in Research Archive Show summary

  Background: In owls, the visual pathways from the retina are totally crossed. Attempts to find ganglion cells with uncrossed axons have failed consistently, when retrograde labeling with HRP is used for their identification. In the present investigation we have used retrograde fluorescent tracers of complementary colour in each optic tectum to demonstrate a tiny population of ipsilaterally-projecting retinal ganglion cells in the owl. Methods: We studied two species, one from each of the two important owl families: the Southern boobook owl, Ninox boobook: (Family Strigidae); and the Barn Owl, Tyto alba: (Family Tytonidae). Results: The small numbers, random distribution and heterogeneity of the mis-projecting ganglion cells, taken together, argue against a functional role for them. Instead, they appear to be the result of developmental errors in the specification of laterality. At a number of different eccentricities and ganglion cell densities, the error rate was roughly a constant fraction of the neurons involved, at aroound 10-4 for the tytonid owl (lacking a fovea) and around 10-5 for the strigid owl (which has a fovea and a higher overall density of ganglion cells). Conclusions: These values are close to the error rates of replicating enzymes, such as nucleic acid polymerases. The evolution of a higher retinal ganglion cell density and a fovea in the Strigidae appears to be accompanied by an improvement in the error rate.

• Popper, A.N.; Fay, R.R.; Platt, C. & Sand, Olav (2003). Sound detection mechanisms and capabilities of teleost fishes. In Collin, Shaun P. & Marshall, N. Justin (Ed.), Sensory Processing in the Aquatic Environment. Springer. ISSN 9780387955278. p. 2–38. Full text in Research Archive
• Sand, Olav (2002). Sound source localization: an historical assessment. Bioacoustics. ISSN 0952-4622. 12(2/3), p. 199–201. Full text in Research Archive Show summary

  Although it was established nearly hundred years ago that fishes do hear, it is still not clear how they locate sound sources. In the sixties, directional hearing in fishes was considered a close range phenomenon dependent on the lateral line, excluding participation of the inner ear (van Bergeijk). Twenty years later the view was that teleost hearing specialists possess a vision like, unambiguous three-dimensional directional hearing in the far field, including distance perception (Schuijf and Buwalda). Vectorial analysis of particle motions of the incident sound is a logical prerequisite for directional hearing in fish. This makes neat models for localization of monopole sources, which generates radial particle motions. However, many biologically significant sources are dipoles and multipoles, where nearfield particle motions are not radial, and the generated frequencies are usually rather low. The near field of low frequency sources extends far beyond the range of the lateral line, and may cover most of the range of the inner ear. Updated models for sound source localization should thus also address localization of dipole and multipole sources in the nearfield. A recent model suggests that fishes do not instantaneously determine the direction to the source, but are guided to it by keeping constant angle between the body axis and the vectorial sound component (Kalmijn). From an historical perspective, it is interesting to note how theories that seemed "scientifically correct" at the time, may have hampered the development of the field. It is certainly not easy for a terrestrial mammal (man) to imagine the sensory possibilities in aquatic species.

• Sand, Olav; Enger, Per Stockfeldt; Karlsen, Hans Erik & Knudsen, Frank Reier (2001). Detection of infrasound in fish and behavioural responses to intense infrasound in juvenile salmonids and european silver eels: a minireview. American Fisheries Society, Symposium. ISSN 0892-2284. Full text in Research Archive
• Grønlien, Heidi Kristine; Løvlie, Arne Mathias & Sand, Olav (2001). Light sensitivity of the ciliate Tetrahymena vorax induced by the fluorescent dye acridine orange. Comparative Biochemistry and Physiology - Part A: Comparative Physiology. ISSN 0300-9629. 130A, p. 633–641. Full text in Research Archive Show summary

  The ciliate Tetrahymena vorax is normally insensitive to light. However, after uptake of acridine orange, blue light evokes instant backward swimming. The dye accumulates mainly in posterior vacuoles, with half-maximal uptake after 1 min. Illumination for 10 s induced a depolarisation of about 15 mV lasting less than 2 s, followed by a sustained hyperpolarisation of about 20 mV. Deciliated cells displayed a similar response. The hyperpolarisation was linked to reduced membrane resistance, showed a reversal potential of about -55 mV and was blocked by 1 mmol l-1 TEA. The rate of rise of electrically evoked Ca2+-spikes was reduced during the hyperpolarisation, which is compatible with elevated cytosolic Ca2+ concentration. This suggests that the hyperpolarisation may be caused by activation of Ca2+-sensitive K+ channels. The depolarisation was abolished in Ca2+-free medium, whereas the hyperpolarisation was unaffected. Illumination for 2 s, or prolonged stimulation restricted to the anterior part of the cell, induced depolarisation only. Illumination of the posterior part caused delayed hyperpolarisation with no preceding depolarisation. We conclude that the induced backward swimming is associated with Ca2+ influx through anterior channels, while Ca2+ released from intracellular stores activates K+ channels responsible for the delayed hyperpolarisation.

• Sand, Olav; Enger, Per S.; Karlsen, Hans Erik & Knudsen, Frank R. (2001). Detection of infrasound in fish and behavioral responses to intense infrasound in juvenile salmonids and European silver eels: a minireview. American Fisheries Society, Symposium. ISSN 0892-2284. 26, p. 183–193. Full text in Research Archive Show summary

  This paper reviews recent studies of infrasound detection in fish and the use if intense infrasound as a fish deterrent. The possible use of intense infrasound in acoustic fish barriers is discussed. Fish are sensitive to infrasound (< 20 Hz), even down to below 1 Hz, and the otolith organs are the sensory system responsible. Particle acceleration, and not sound pressure, is the relevant sound parameter for low frequency detection in fish, and the threshold values are in the range 10-5-10-4 m/s2. The hydrodynamic noise generated by swimming fish is mainly in the infrasound range, and may be important in prey-predator interactions. An infrasound source able to generate large near-field particle acceleration has been employed to divert downstream migrating Atlantic salmon (Salmo salar) smolts in a small river. At the observation site the river branched into a main course and a minor channel. The infrasound source was positioned in the channel, and at intensities above 10-2 ms-2 the 10 Hz sound effectively blocked passage of smolts through this alternative route. An improved version of the original infrasound source has been employed to test the effect of intense infrasound on downstream migrating European silver eels (Anguilla anguilla). The tests were carried out in a river where a trap that catches all the descending eels is installed near the river mouth. The trap was separated in four equal sections. During the periods with infrasound exposure, the proportion of silver eels entering the section closest to the sound source was reduced to 43 % of the control value. In the section closest to the opposite river bank, infrasound increased the proportion of trapped eels to 144 % of the control values. We conclude that intense infrasound has a great potential in acoustic fish barriers.

• Sand, Olav; Chen, Bo-Ming & Grinnell, Alan D. (2001). Contribution of L-type Ca2+ channels to evoked transmitter release in cultured Xenopus nerve-muscle synapses. Journal of Physiology. ISSN 0022-3751. 536, p. 21–33. Full text in Research Archive Show summary

  Simultaneous pre- and postsynaptic patch recordings were obtained from the varicosity synapses formed by Xenopus motoneurons on muscle cells in embryonic cultures, in order to elucidate the contribution of N- and L-type Ca2+ channels to the varicosity Ca2+ current (ICa) and evoked transmitter release.Although N-type channels are predominant in the varicosities and generally thought to be responsible for all evoked release, in most synapses a fraction of ICa and release could be reversibly blocked by the L-type channel antagonist nifedipine, and enhanced by the agonist Bay K8644. Up to 50 % (mean 21 %) of the ICa evoked by a voltage clamp waveform mimicking a normal presynaptic action potential (APWF) is composed of L-type current. Surprisingly, the nifedipine-sensitive (L) channels activated more rapidly (time-constant 0.44 ms) than the nifedipine-insensitive (N) channels (time constant 1.14 ms). Thus the L-type current would play a disproportionate role in the ICa to a normal action potential. The relationship between ICa and release was the same for nifedipine-sensitive and -resistant components. The N- and L-components of ICa are thus equally potent in evoking release. This may represent an immature stage before N-type channels become co-localized with the release sites. Replacing Ca2+ in the medium with Ba2+ strongly enhanced the L-type component, suggesting that L-type channels may be inactivated at Ca2+ levels close to those at rest. We speculate that populations of L-type channels in different parts of the neuron may be recruited or inactivated by fluctuations of the cytosolic Ca2+-concentration within the physiological range. Simultaneous pre- and postsynaptic patch recordings were obtained from the varicosity synapses formed by Xenopus motoneurons on muscle cells in embryonic cultures, in order to elucidate the contribution of N- and L-type Ca2+ channels to the varicosity Ca2+ current (ICa) and evoked transmitter release.Although N-type channels are predominant in the varicosities and generally thought to be responsible for all evoked release, in most synapses a fraction of ICa and release could be reversibly blocked by the L-type channel antagonist nifedipine, and enhanced by the agonist Bay K8644. Up to 50 % (mean 21 %) of the ICa evoked by a voltage clamp waveform mimicking a normal presynaptic action potential (APWF) is composed of L-type current. Surprisingly, the nifedipine-sensitive (L) channels activated more rapidly (time-constant 0.44 ms) than the nifedipine-insensitive (N) channels (time constant 1.14 ms). Thus the L-type current would play a disproportionate role in the ICa to a normal action potential. The relationship between ICa and release was the same for nifedipine-sensitive and -resistant components. The N- and L-components of ICa are thus equally potent in evoking release. This may represent an immature stage before N-type channels become co-localized with the release sites. Replacing Ca2+ in the medium with Ba2+ strongly enhanced the L-type component, suggesting that L-type channels may be inactivated at Ca2+ levels close to those at rest. We speculate that populations of L-type channels in different parts of the neuron may be recruited or inactivated by fluctuations of the cytosolic Ca2+-concentration within the physiological range. Simultaneous pre- and postsynaptic patch recordings were obtained from the varicosity synapses formed by Xenopus motoneurons on muscle cells in embryonic cultures, in order to elucidate the contribution of N- and L-type Ca2+ channels to the varicosity Ca2+ current (ICa) and evoked transmitter release.Although N-type channels are predominant in the varicosities and generally thought to be responsible for all evoked release, in most synapses a fraction of ICa and release could be reversibly blocked by the L-type channel antagonist nifedipine, and enhanced by the agonist Bay K8644. Up to 50 % (mean 21 %) of the...

• Sand, Olav & Karlsen, Hans Erik (2000). Detection of infrasound and linear acceleration in fish. Philosophical Transactions of the Royal Society of London. Biological Sciences. ISSN 0962-8436. 355, p. 1295–1298. Full text in Research Archive Show summary

  Fish have an acute sensitivity to extremely low frequency linear acceleration, or infrasound, even down to below 1 Hz. The otolith organs are the sensory system responsible for this ability. It is likely that infrasound is an important source of information about the environment of the fish. Seismic motion of the sea floor and turbulence caused by ocean currents are among the sources of the high level of ambient infrasound in the oceans. The pattern of ambient infrasound may be used for orientation in migratory fish. Pelagic fish may also detect changes in the surface wave pattern associated with altered water depth and distant land formations. The possible existence of inertial guidance in fish is compatible with an acute sensitivity to linear acceleration, which may also be used to detect the relative velocity of layered ocean currents. The hydrodynamic noise generated by swimming fish is mainly in the infrasound range, and infrasound is particularly potent in eliciting behavioural responses in fish. Acute sensitivity to infrasound may be a widespread ability among aquatic organisms, and have also been reported in cephalopods and crustaceans.

• Østberg, Bjørn Christian; Sand, Olav; Bjøro, Trine & Haug, Egil (2000). A perfusion system for studying secretion in vitro using a cell column optimised to provide high time resolution. BioTechniques. ISSN 0736-6205. 29, p. 1114–1125. Full text in Research Archive Show summary

  To study the secretion from endocrine cells in culture, we have developed a cell column perfusion system with a time resolution of 4 s. The core of the system is a perfusion chamber with a cell supporting matrix of monosized polystyrene beads. The particles are solid and can withstand a high pressure gradient without deformation. The minimum amount of cell material required to obtain detectable levels of secretory products is a function of the assay sensitivity, perfusion flow, fraction volume and hence time resolution. The volume of the perfusion chamber is therefore adjustable, in order to satisfy varying demands of minimum cell number. The general flow characteristics of the system were characterised using radiolabelled substances of various molecular sizes. Employing the system in secretory studies of rat pituitary tumour cells (GH4C1), we have identified differences in secretion profiles related to the kinetics of the different transmembrane and intracellular mechanisms involved.

• Rudberg, Pia & Sand, Olav (2000). Bistable membrane potential of the ciliate coleps hirtus. Journal of Experimental Biology. ISSN 0022-0949. 203, p. 757–764. Full text in Research Archive Show summary

  In normal solution the swimming pattern of the freshwater ciliate Coleps hirtus, belonging to the class Prostomatea, consists of alternating periods of nearly linear forward swimming and circular swimming within a small area. Current clamp recordings were performed in order to elucidate the mechanism for this behaviour. No members of this class have previously been studied with electrophysiological techniques. The ciliates were kept in culture feeding on the planctonic alga Rhodomonas minuta. The membrane potential showed spontaneous shifts between a deep and a shallow level of about -50 mV and -30 mV. The input resistance and capacitance at the deep level were about 400 M* and 120 pF. C. hirtus displayed a pronounced inward rectification, which was nearly insensitive to 1 mM Cs+ and almost completely blocked by 1 mM Ba2+. Depolarising current injections failed to evoke graded, regenerative Ca2+-spikes. However, current-induced depolarisations from the deep potential level showed a pronounced shoulder during the repolarising phase. Increased current injections prolonged the shoulder, which occasionally stabilised at the shallow membrane potential. The membrane potential could be shifted to the deep level by brief hyperpolarising current injections. Similar biphasic membrane properties have previously not been reported in any ciliate. The bistability of the membrane potential was abolished in Ca2+-free solution containing Co2+ or Mg2+. In Ca2+-free solution containing 1 mM Ba2+ brief depolarising current injections at the deep potential level evoked all-or-nothing action potentials with a prolonged plateau coinciding with the shallow potential. We conclude that the deep membrane potential in C. hirtus corresponds to the traditional resting potential, whereas the shallow level is a Ca2+-dependent plateau potential. In normal solution the direction of the ciliary beat was backward at the deep potential level and forward at the shallow membrane potential, probably reflecting the two main phases of the swimming pattern.

• Sand, Olav; Enger, Per S.; Karlsen, Hans Erik; Knudsen, Frank R. & Kvernstuen, Torstein (2000). Avoidance responses to infrasound in downstream migrating European silver eels, Anguilla anguilla. Environmental Biology of Fishes. ISSN 0378-1909. 57, p. 327–336. Full text in Research Archive Show summary

  In an attempt to develop an efficient acoustic fish fence, we have designed an infrasound source able to generate large nearfield particle acceleration. The source generates water movements by means of two symmetrical pistons in an air-filled cylinder with 21 cm bore. The pistons are driven by eccentric coupling to an electric motor, with 5 cm p.p. amplitude. The piston movements are 180° out of phase. The piston reaction forces are thus opposed, leading to vibration free operation. The submergible infrasound source is operated freely suspended in the water mass. The emitted sound frequency is 11.8 Hz. The particle acceleration is about 0.01 ms-2 at a distance of 3 m, corresponding to the threshold intensity for deterring effects of infrasound on Atlantic salmon smolts. The sound source was employed to test the effect of intense infrasound on migrating European silver eels. Fish confined in a tank displayed startle behaviour and prolonged stress reactions, telemetrically monitored as tachycardia, in response to intense infrasound. The field tests were carried out in the River Imsa. A trap that catches all the descending eels is installed near the river mouth. The trap was separated in four equal sections. During the periods with infrasound exposure, the proportion of silver eels entering the section closest to the sound source was reduced to 43% of the control value. In the section closest to the opposite river bank, infrasound increased the proportion of trapped eels to 144% of the control values. This shift of the migrating eels away from the infrasound source was highly significant.

• Hafting, Torkel & Sand, Olav (2000). Purinergic activation of BK channels in clonal kidney cells (Vero cells). Acta Physiologica Scandinavica. ISSN 0001-6772. 170, p. 99–109. Full text in Research Archive Show summary

  We have studied the activation of a high conductance channel in clonal kidney cells from African green monkey (Vero cells) using patch clamp recordings and micro-fluorometric (fura-2) measurements of cytosolic Ca2+. The single-channel conductance in excised patches is 170 pS in symmetrical 140 mM KCl. The channel is highly selective for K+ and activated by membrane depolarisation and application of Ca2+ to the cytoplasmatic side of the patch. The channel is thus a BK-channel. Cell-attached recordings revealed that the channel is inactive in unstimulated cells. Extracellular application of less than 0.1 µM ATP transiently increased the cytosolic Ca2+ concentration ([Ca2+]i) to about 550 nM, and induced membrane hyperpolarisation due to Ca2+-activated K+ currents. ATP-stimulation also activated BK-channels in cell-attached patches at both the normal resting potential and during membrane hyperpolarisation. The increase in [Ca2+]i was due to Ca2+-release from internal stores, suggesting that Vero cells express G-protein coupled purinergic receptors (P2Y) mediating IP3-induced release of Ca2+. The P2Y receptors were sensitive to both UTP and ADP, and the rank of agonist potency was ATP >> UTP ³ ADP. This result indicates the presence of both P2Y1 and P2Y2 receptors or a receptor subtype with untypical agonist sensitivity. It has previously been shown that hypotonic challenge activate BK-channels in both normal and clonal kidney cells. The subsequent loss of KCl may be an important factor in cellular volume regulation. Our results support the idea of an autocrine role of ATP in this process. A minute release of ATP induced by hypotonically evoked membrane stretch may activate the P2Y receptors, subsequently increasing [Ca2+]i and thus causing K+ efflux through BK channels.

• Bjålie, J.G.; Haug, Egil; Sand, Olav & Sjaastad, Øystein (1998). Menneskekroppen. Fysiologi og anatomi, Menneskekroppen. Fysiologi og anatomi. Universitetsforlaget. ISSN 9788200418313. p. 1–486. Full text in Research Archive
• Sand, Olav (1997). Infrasonic detection in fish. In Carlson, T.J. & Popper, A.N. (Ed.), Using Sound to modify Fish Behavior at Power-Production and Water-Control Facilities: a Workshop. Bonneville Power Administration,. p. 91–105. Full text in Research Archive
• Kajiwara, R.; Sand, Olav; Kidokoro, Y.; Barish, M.E. & Iijima, T. (1997). Functional organization of chromaffin cells and cholinergic synaptic transmission in rat adrenal medulla. Japanese Journal of Physiology. ISSN 0021-521X. 47, p. 449–464. Full text in Research Archive
• Knudsen, Frank R.; Schreck, C.B.; Knapp, S.M.; Enger, Per S. & Sand, Olav (1997). Infrasound produces flight and avoidance responses in Pacific juvenile salmonids. Journal of Fish Biology. ISSN 0022-1112. 51, p. 824–829. Full text in Research Archive
• Haugstad, Tor S.; Karlsen, Hans Erik; Krajci, Peter; Due-Tønnessen, Bernt; Larsen, M & Sandberg, Cecilie [Show all 9 contributors for this article] (1997). Efflux of _g-aminobutyric acid caused by changes in ion concentrations and cell swelling simulating the effect of cerebral ischaemia. Acta Neurochirurgica. ISSN 0001-6268. 139, p. 453–463. Full text in Research Archive
• Haug, Trude M & Sand, Olav (1997). BK channels in intact clonal rat pituitary cells are activated by physiological elevations of the cytosolic Ca2+ concentration at the normal resting potential. Acta Physiologica Scandinavica. ISSN 0001-6772. 161, p. 227–237. Full text in Research Archive
• Lanzrein, Markus; Falnes, P.Ø.; Sand, Olav & Olsnes, Sjur (1997). Structure-function relationship of the ion channel formed by diphtheria toxin in Vero cell membrane. Journal of Membrane Biology. ISSN 0022-2631. 156, p. 141–148. Full text in Research Archive
• Bourke, J.R.; Abel, K.C.; Huxham, G.J.; Sand, Olav & Manley, S.W. (1996). Sodium channel heterogeneity in the apical membrane of porcine thyroid epithelial cells. Journal of Endocrinology. ISSN 0022-0795. 149, p. 101–108. Full text in Research Archive

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• Sand, Olav; Sjaastad, Øystein & Haug, Egil (2022). Menneskets fysiologi, 3. utgave. Gyldendal Akademisk. ISBN 9788205534599. 912 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein; Haug, Egil & Bjaalie, Jan G. (2021). Människokroppen - Fysiologi och anatomi, 3. upplagan. Liber. ISBN 9789147142873. 668 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein; Haug, Egil & Bjaalie, Jan G. (2019). Anatomi og fysiologi - Menneskekroppen, 4. utgave. Gads Forlag. ISBN 9788712058328. 666 p. Full text in Research Archive
• Sjaastad, Øystein; Toverud, Kari C.; Sand, Olav; Bjaalie, Jan G. & Egil, Haug (2018). Arbeidsbok til Menneskekroppen - Fysiologi og anatomi, 3. utgave. Gyldendal Akademisk. ISBN 9788205514034. 224 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein; Haug, Egil & Bjaalie, Jan G. (2018). Menneskekroppen - Fysiologi og anatomi, 3. utgave. Gyldendal Akademisk. ISBN 9788205504820. 666 p. Full text in Research Archive
• Sjaastad, Øystein; Sand, Olav & Hove, Knut (2017). Fiziologija domacih zivotinja. Naklada Slap. ISBN 9789531918589. 803 p. Full text in Research Archive
• Sjaastad, Øystein; Sand, Olav & Hove, Knut (2016). Physiology of Domestic Animals - Third Edition. Scandinavian Veterinary Press. ISBN 9788291743417. 936 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein; Haug, Egil & Bjaalie, Jan G. (2015). Menneskets anatomi og fysiologi 3. utgave. Gads Forlag. ISBN 9788712051077. 538 p. Full text in Research Archive
• Sjaastad, Øystein; Toverud, Kari C.; Sand, Olav; Bjaalie, Jan G. & Egil, Haug (2015). Studieoppgaver til Menneskets anatomi og fysiologi. Gads Forlag. ISBN 9788712050353. 203 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein & Haug, Egil (2014). Menneskets fysiologi, 2. utgave. Gyldendal Akademisk. ISBN 9788205423411. 885 p. Full text in Research Archive
• Sjaastad, Øystein; Sand, Olav & Hove, Knut (2013). Fisiologia degli animali domestici. Casa Editrice Ambrosiana. ISBN 9788808182937. 816 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein; Haug, Egil & Bjaalie, Jan G. (2011). Ihminen - Fysiologia ja anatomia. Sanoma Pro Oy. ISBN 9789526308982. 571 p. Full text in Research Archive
• Sjaastad, Øystein; Sand, Olav & Hove, Knut (2010). Physiology of Domestic Animals, Second Edition. Scandinavian Veterinary Press. ISBN 9788291743073. 804 p. Full text in Research Archive
• Sjaastad, Øystein; Toverud, Kari C.; Sand, Olav; Bjaalie, Jan G. & Haug, Egil (2008). Arbetsbok till Människokroppen-Fysiologi och anatomi, andra upplagen. Liber. ISBN 9789147015351. 203 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein; Egil, Haug & Bjaalie, Jan G. (2007). Människokroppen - Fysiologi och anatomi. Liber. ISBN 9789147084357. 544 p. Full text in Research Archive
• Sjaastad, Øystein V.; Toverud, Kari C.; Sand, Olav; Bjaalie, Jan G. & Haug, Egil (2006). Arbeidsbok til menneskekroppen - Fysiologi og anatomi, 2. utgave. Gyldendal Akademisk. ISBN 9788205348080. 203 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein; Haug, Egil & Bjaalie, Jan G. (2006). Menneskekroppen - Fysiologi og anatomi 2. utgave. Gyldendal Akademisk. ISBN 9788205348073. 544 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein & Haug, Egil (2004). Människans fysiologi. Liber. ISBN 9789147051953. 600 p. Full text in Research Archive
• Sjaastad, Øystein; Toverud, Kari C.; Sand, Olav; Bjaalie, Jan G. & Haug, Egil (2003). Ihminen - Fysiologian ja anatomian työkirja. WSOY. ISBN 9789510248249. 189 p. Full text in Research Archive
• Sjaastad, Øystein; Toverud, Kari C.; Sand, Olav; Bjaalie, Jan G. & Haug, Egil (2003). Arbetsbok till Människokroppen - Fysiologi och anatomi. Liber. ISBN 9789147051847. 189 p. Full text in Research Archive
• Sjaastad, Øystein; Toverud, Kari C.; Sand, Olav; Bjaalie, Jan G. & Haug, Egil (2003). Arbejdsbog til Menneskets anatomi og fysiologi. Gads Forlag. ISBN 9788712039839. 189 p. Full text in Research Archive
• Sjaastad, Øystein; Hove, Knut & Sand, Olav (2003). Physiology of Domestic Animals. Scandinavian Veterinary Press. ISBN 9788291743110. 735 p. Full text in Research Archive
• Sjaastad, Øystein; Toverud, Kari C.; Sand, Olav; Bjålie, Jan Gunnar & Haug, Egil (2002). Arbeidsbok til Menneskekroppen. Fysiologi og anatomi. Gyldendal Akademisk. ISBN 9788200451181. 189 p. Full text in Research Archive
• Sand, Olav; Sjaastad, Øystein & Haug, Egil (2001). Menneskets fysiologi. Gyldendal Norsk Forlag A/S. ISBN 9788205280748. 600 p. Full text in Research Archive
• Bjaalie, Jan G.; Egil, Haug; Sand, Olav & Sjaastad, Øystein (1999). Ihminen - Fysiologia ja anatomia. WSOY. ISBN 9789510230879. 510 p. Full text in Research Archive
• Bjaalie, Jan G.; Egil, Haug; Sand, Olav & Sjaastad, Øystein (1998). Människokroppen. Liber. ISBN 9789147049196. 486 p. Full text in Research Archive
• Bjaalie, Jan G.; Haug, Egil; Sand, Olav & Sjaastad, Øystein (1998). Menneskets anatomi og fysiologi. Gads Forlag. ISBN 9788712032649. 486 p. Full text in Research Archive
• Bjaalie, Jan G.; Egil, Haug; Sand, Olav & Sjaastad, Øystein (1998). Menneskekroppen. Gyldendal Norsk Forlag A/S. ISBN 9788200418313. 486 p. Full text in Research Archive

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• Hawkins, Anthony D.; Chapman, Colin; Fay, Richard R.; Horner, Kathleen; Popper, Arthur N. & Sand, Olav (2019). The pioneering contributions of Per Stockfleth Enger to fish bioacoustics. Journal of the Acoustical Society of America. ISSN 0001-4966. 145(3), p. 1596–1599. doi: 10.1121/1.5095405. Full text in Research Archive
• Sand, Sverre L.; Nissen-Meyer, Jon; Sand, Olav & Haug, Trude M (2011). The cationic peptide plantaricin A produced by Lactobacillus plantarum permeabilizes eukaryotic cell membranes by a mechanism dependent on negative surface charge linked to glycosylated membrane proteins. Acta Physiologica. ISSN 1748-1708. 202, p. P56–P56. Full text in Research Archive
• Haug, Trude M; Sand, Sverre L.; Phung, Danh; Hardy, Simpn P. & Sand, Olav (2009). The Bacillus cereus Nhe enterotoxin forms gigantic channels in cell membranes. Acta Physiologica. ISSN 1748-1708. 196, p. P30–P30. Full text in Research Archive Show summary

  The Nhe enterotoxin was discovered following a large food-poisoning outbreak in Norway in 1995, and consists of three separate proteins: Nhe-A, -B, and -C. The Nhe complex induces cell lysis in clonal epithelial cell lines (Vero and Caco2), and forms channels of 200-700 pS conductance in planar lipid bilayers (Fagerlund et al. 2008). Electrophysiological effects of Nhe on cell membranes have previously not been examined. We have studied the membrane effects of Nhe on Vero cells and clonal pituitary cells (GH4 cells) by patch clamp recordings and microfluorometric (fura-2) monitoring of the cytosolic Ca2+ level ([Ca2+]i ) and fluorochrome concentration. Cell lysis was assessed by measuring the release of lactate dehydrogenase (LDH). Within 30 min, preparations of Nhe from 5 hr culture supernatants of B. cereus NVH75/95 induced massive LDH release, i.e., 90-100 % of maximum (triton X-100) in both cell types. Whole-cell voltage clamp recordings revealed Nhe-induced insertion of gigantic channels after a delay of 1-3 min. The mean single channel conductance was estimated to 8 nS, which is more than 10 times the mean channel conductance in planar lipid bilayers. The reversal potential of the channel currents was close to 0 mV, indicating an unselective channel. To our knowledge, this is the highest channel conductance reported in cell membranes under quasi-physiological conditions. Nhe also increased [Ca2+]i abruptly to saturating levels after a similar delay, followed by a gradual loss of fluorochrome from the cytosol. We conclude that the Nhe toxin complex induces cell lysis by forming large conductance channels in the plasma membrane of target epithelia. Reference: Fagerlund A., Lindbäck T., Storset A.K., Granum P.E. and Hardy S.P. 2008. Microbiology 154, 693-704.

• Andersland, Kristin; Johansen, Guro Five; Haug, Trude M & Sand, Olav (2008). THE ANTIMICROBIAL PEPTIDE PLANTARICIN A PERMEABILIZES LIVER AND KIDNEY CELLS. Acta Physiologica. ISSN 1748-1708. 193, p. P17–P17. Full text in Research Archive
• Sand, Sverre L.; Ohara, S.; Oppegård, Camilla; Iijima, Toshio; Blomhoff, Heidi Kiil & Nissen-Meyer, Jon [Show all 7 contributors for this article] (2008). BOTH NORMAL AND CANCEROUS LYMPHOCYTES AND NEURONS ARE PERMEABILIZED BY PLANTARICIN A, A PEPTIDE PRODUCED BY LACTOBACILLUS PLANTARUM. Acta Physiologica. ISSN 1748-1708. 193, p. P18–P18. Full text in Research Archive
• Sand, Olav (2008). Zoofysiologen John Olav Krog. In Lærum, Ole Didrik (Eds.), Norske Forskerprofiler, 2006-2007. Fagbokforlaget. ISSN 9788245008487. p. 188–193. Full text in Research Archive
• Sand, Olav; Karlsen, Hans Erik & Knudsen, FR (2008). Comment on "Silent research vessels are not quiet" [J. Acoust. Soc. Am. 121, EL145-EL1501 (L). Journal of the Acoustical Society of America. ISSN 0001-4966. 123, p. 1831–1833. doi: 10.1121/1.2839134. Full text in Research Archive
• Haug, Trude M; Hodne, Kjetil; Weltzien, Finn-Arne & Sand, Olav (2007). Signaling properties of teleost gonadotropes with a first study from atlantic cod. Acta Physiologica. ISSN 1748-1708. 190, p. 504–504. Full text in Research Archive
• Kristiansen, Per Eugen; Sand, Sverre; Haug, Trude M; Sand, Olav; Fimland, Gunnar & Zhao, Hongxia [Show all 10 contributors for this article] (2006). Structure and Mode of Action of the Membrane-Permeabilizing Antimicrobial Peptide Pheromone Plantaricin A. Full text in Research Archive
• Haug, Trude M; Hodne, Kjetil; Weltzien, Finn-Arne & Sand, Olav (2006). Electrophysiological properties of pituitary cells in primary cultures from atlantic cod (Gadus morhua). Acta Physiologica. ISSN 1748-1708. 187, p. P23–P23. Full text in Research Archive
• Sand, Sverre Larsstuvold; Haug, Trude M; Fimland, Gunnar; Nissen-Meyer, Jon & Sand, Olav (2006). Membrane-permeabilizing effects of the bacterial peptide Plantaricin A on rat anterior pituitary cells. Acta Physiologica. ISSN 1748-1708. 187, p. P11–P11. Full text in Research Archive
• Sand, Olav (2006). Directional hearing in fish: a minireview. Acta Physiologica. ISSN 1748-1708. 187, p. 0802–0802. Full text in Research Archive
• Sand, Sverre L.; Haug, Trude M; Nissen-Meyer, Jon & Sand, Olav (2006). Clonal rat anterior pituitary cells (GH4 cells) are permeabilized by plantaricin A, a peptide pheromone produced by Lactobacillus plantarum. SFN Abstract Viewer/Itinerary Planner. Full text in Research Archive Show summary

  Antimicrobial peptides and proteins, generally referred to as bacteriocins, are produced by numerous strains of bacteria. Plantaricin A (PlnA) is a 26-mer peptide pheromone that induces bacteriocin production in the strain from which it is released, Lactobacillus plantarum C11. Although pheromone activity is the prime biological function of PlnA, the peptide also has membrane-permeabilizing strain-specific antibacterial activity. The pheromone activity of PlnA depends on its binding to specific receptors, preceded by a non-chiral interaction with the target cell membrane. The latter mechanism is presumably responsible for the membrane-permeabilizing effect on sensitive strains. We have studied the effect of PlnA on the GH4 cell line using the patch clamp techniques. This neoplastic cell line is derived from a rat anterior pituitary tumor, and is commonly used as a model system for anterior pituitary cells. Whole-cell current clamp recordings revealed massive membrane permeabilization within 5 s after exposure to 10-100 µM PlnA. The membrane depolarized to abut 0 mV and the membrane resistance decreased to a mere fraction of the initial value after less than 1 min. Recordings from outside-out patches during exposure to 10 µM PlnA showed that the induced membrane current reversed at 0 mV, indicating an unspecific conductance increase. The D-form of the peptide, composed of only D-amino acids, was as effective as the L-form, indicating that PlnA exerts its membrane-permeabilizing effect through a non-chiral mechanism. Recordings from inside-out patches during exposure of the internal leaflet of the cell membrane to 1 mM PlnA showed both unaltered membrane conductance and BK channel activity. These results suggest that the peptide does not interfere with the membrane integrity when the inner leaflet is exposed. Surprisingly, the normal counterparts of the GH4 cell line, primary cell cultures of rat anterior pituitary, were insensitive to the peptide. Even at a concentration of 1 mM, PlnA had no detectable effects on the membrane conductance of normal anterior pituitary cells in any of the patch clamp configurations. Thus, the peptide seems to differentiate not only between membrane leaflets, but also between plasma membranes. This characteristic makes the membrane permeabilizing effects of PlnA particularly intriguing.

• Grønlien, Heidi Kristine; Sand, Olav & Berg, Trond (2005). Phagocytosis in the polymorphic ciliate Tetrahymena vorax. Acta Physiologica Scandinavica. ISSN 0001-6772. 183, p. A422–A422. Full text in Research Archive
• Hagen, Bjarne; Grønlien, Heidi Kristine & Sand, Olav (2005). A study of chemokinesis in the two forms of the polymorphic ciliate Tetrahymena vorax. Acta Physiologica Scandinavica. ISSN 0001-6772. 183, p. A423–A423. Full text in Research Archive
• Sand, Olav; Haug, Trude M & Mørk, Halvor (2005). Electrophysiological properties of anterior pituitary cells. Acta Physiologica Scandinavica. ISSN 0001-6772. 183, p. A402–A402. Full text in Research Archive
• Haug, Trude M; Hafting, Torkel & Sand, Olav (2004). Contribution of BK channels to the resting conductance and the second phase of the response to TRH in anterior pituitary cells (GH4C1cells). Acta Physiologica Scandinavica. ISSN 0001-6772. 181, p. A140–A140. Full text in Research Archive
• Mørk, Halvor; Haug, Trude M & Sand, Olav (2004). Contribution of different Ca2+-activated K+-channels to the first phase of the TRH response in clonal anterior pituitary cells (GH4 cells). Acta Physiologica Scandinavica. ISSN 0001-6772. 181, p. A140–A140. Full text in Research Archive
• Haug, Trude M; Hafting-Fyhn, Torkel & Sand, Olav (2003). Contribution of BK channels to the second phase of the response to TRH in anterior pituitary cells (GH4 cells). SFN Abstract Viewer/Itinerary Planner. Full text in Research Archive
• Sand, Olav; Chen, Bo-Ming & Grinnell, Alan D. (2001). Presynaptic terminals of embryonic Xenopus neuromuscular junctions possess L-type calcium channels with fast activation kinetics. Pflügers Archiv: European Journal of Physiology. ISSN 0031-6768. 441(6), p. 167–167. Full text in Research Archive
• Sand, Olav; Chen, Bo-Ming & Grinnell, Alan D. (2000). L-type calcium channels contribute to evoked transmitter release in embryonic Xenopus nerve muscle synapses. Abstracts - Society for Neuroscience. ISSN 0190-5295. 26, p. 1091–1091. Full text in Research Archive
• Hafting, Torkel & Sand, Olav (1999). Purinergic activation of BK channels in Vero cells. Abstracts - Society for Neuroscience. ISSN 0190-5295. 25, p. 1694–1694. Full text in Research Archive
• Hafting, Torkel & Sand, Olav (1999). Purinergic activation of BK-channels in intact Vero cells at the normal resting potential. Acta Physiologica Scandinavica. ISSN 0001-6772. 165, p. A46–A46. Full text in Research Archive
• Bruskeland, G.E. & Sand, Olav (1999). Membrane currents in the microstome and macrostome forms of Tetrahymena vorax. Acta Physiologica Scandinavica. ISSN 0001-6772. 165, p. A46–A46. Full text in Research Archive
• Grønlien, Heidi Kristine; Løvlie, Arne Mathias & Sand, Olav (1998). Light sensitivity of the ciliate Tetrahymena vorax induced by a fluorent dye. European Journal of Neuroscience. ISSN 0953-816X. 435, p. 123–123. Full text in Research Archive
• Haug, Trude M & Sand, Olav (1997). BK-channels in cell-attached patches of clonal pituitary cells (GH4 cells). Abstracts - Society for Neuroscience. ISSN 0190-5295. 23(2), p. 1481–1481. Full text in Research Archive

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