Light-evoked depolarizations in the retina of Strombus: role of calcium and other divalent cations.
Previous studies indicate that overlapping inward sodium and outward potassium currents play a role in generating the waveform of light-evoked depolarizations (LEDs) in one type of retinal neuron in Strombus luhuanus, a marine gastropod [Chinn, K. S., and Gillary, H. L. (1985). Comp. Biochem. Physiol. 80A:233-245]. This paper concerns the effects of divalent cations on the LED. The LED can exhibit a distinct early phase of depolarization (DE). Increasing the [Ca2+] in the artificial seawater (ASW) bathing medium reduced the amplitude of the entire LED, and omitting Ca2+ increased it. Adding 10 mM Sr2+ or 10 mM Mn2+ to either normal ASW or 0-Ca2+ ASW decreased the LED amplitude. Adding 10 mM Ba2+ to 0-Ca2+ ASW also decreased the LED amplitude, but adding Ba2+ to normal ASW selectively increased DE. Cd2+ (100 microM) selectively reduced DE when added to normal ASW but not when added to 0-Ca2+ ASW. The results show that a variety of divalent cations can alter the currents that underlie the LED. They also suggest that an inward Ca2+ current occurs during DE.
D000818:Animals; D001464:Barium / Q000378:metabolism; D002104:Cadmium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent / Q000378:metabolism; D004594:Electrophysiology; D008345:Manganese / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation; D012160:Retina / Q000166:cytology*; D012908:Snails / Q000502:physiology*; D013324:Strontium / Q000378:metabolism
D002413:Cations, Divalent; D002104:Cadmium; D001464:Barium; D008345:Manganese; D002118:Calcium; D013324:Strontium