Light-evoked depolarizations in the retina of Strombus: role of sodium and potassium ions.
Light-evoked depolarizations (LED's) in retinal cells of Strombus luhuanus can exhibit an early phase of depolarization (DE), a brief repolarizing phase (RE), and a later depolarizing phase (DL). Lowering external Na+ by substitution with choline, tetramethylammonium or sucrose, reduced the amplitude of the entire LED, but DL was reduced more than DE. Replacement of Na+ with Li+ reduced DE more than DL. Lowering pH reduced DL more than DE, while raising it increased DL but not DE. K+ channel blocking agents, tetraethylammonium and 4-aminopyridine, increased RE. During the LED, cell membrane conductance increased in two phases, corresponding to DE and DL. The results suggest LED generation by two separable conductance increases to Na+, corresponding to DE and DL, and another to K+ during RE.
Chinn
K S
KS
Gillary
H L
HL
D015761:4-Aminopyridine; D000222:Adaptation, Physiological; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000187:drug effects; D008094:Lithium / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000502:physiology; D010775:Photic Stimulation; D011188:Potassium / Q000502:physiology*; D012160:Retina / Q000166:cytology / Q000502:physiology*; D012908:Snails / Q000502:physiology*; D012964:Sodium / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D000631:Aminopyridines; D007473:Ion Channels; D013779:Tetrodotoxin; D008094:Lithium; D012964:Sodium; D015761:4-Aminopyridine; D011188:Potassium