Voltage clamp study of electrophysiologically-identified horizontal cells in carp retina.
Passive membrane properties and electromotive force of light modulated currents of L-, R/G-type and rod-driven horizontal cells were studied by voltage-clamp using double-barrelled micro-electrodes whilst perfusing with 5 microM dopamine to uncouple the gap junctions. Input impedances of horizontal cells in darkness were 31 +/- 1.4 M omega (mean +/- SE, n = 63); the resting potentials were -37 +/- 1.3 mV. Current-voltage relationships had regions of both inward and outward rectification and a region of negative resistance was commonly observed. Reversal potentials of light modulated currents were estimated on average to be -7 +/- 4 mV (n = 14), which is consistent with the involvement of K+ and Na+ and/or Ca2+ gradients. Importantly in R/G cells both depolarizing and hyperpolarizing components of the response had essentially the same reversal potential.
Low
J C
JC
Imperial College of Science, Technology and Medicine, Department of Biology, London, U.K.
Yamada
M
M
Djamgoz
M B
MB
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002347:Carps / Q000502:physiology*; D003623:Dark Adaptation; D004594:Electrophysiology; D007473:Ion Channels / Q000502:physiology; D008564:Membrane Potentials; D008839:Microelectrodes; D009474:Neurons / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D012160:Retina / Q000502:physiology*; D012964:Sodium / Q000378:metabolism
D007473:Ion Channels; D012964:Sodium; D011188:Potassium; D002118:Calcium