Regenerative sodium and calcium currents in goldfish retinal ganglion cell somata.
Whole-cell patch-clamp recordings were made from isolated goldfish retinal ganglion cell somata. Sodium- and calcium-dependent action potentials--blocked with tetrodotoxin (TTX) and Co2+ ions, respectively--were evoked under current-clamp. Depolarization of these somata under voltage clamp activated distinguishable Na+ and Ca2+ conductances: the former was permeable to Na+, blocked by TTX, impermeable to N-methyl-D-glucamine and tris(hydroxymethyl)aminomethane, and began to activate around -45 mV; the latter were permeable to Ca2+, but not Co2+, and began to activate around -55 mV. These results are consistent with recordings from carp, frog, salamander and rat retinal ganglion cells.
Ishida
A T
AT
Department of Animal Physiology, University of California, Davis 95616.
D000818:Animals; D015220:Calcium Channels / Q000502:physiology*; D003035:Cobalt / Q000494:pharmacology; D006054:Goldfish / Q000502:physiology*; D008536:Meglumine / Q000494:pharmacology; D008564:Membrane Potentials; D008839:Microelectrodes; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000502:physiology*; D015222:Sodium Channels / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D015220:Calcium Channels; D015222:Sodium Channels; D003035:Cobalt; D013779:Tetrodotoxin; D008536:Meglumine