Intracellular Ca2+ and adaptation of voltage responses to light in Hermissenda photoreceptors.
Fluorescent imaging of Ca2+ and intracellular recordings were used to assess Ca2+ increases and voltage responses during light presentations in Hermissenda B photoreceptors. Ca2+ levels increased and were sustained during a relatively long exposure to light. Repeated presentations of a brief light induced an elevation of intracellular Ca2+ that persisted throughout short interlight intervals, but which dissipated during long interlight intervals. In all instances, the magnitude of the intracellular Ca2+ signal was inversely related to the amplitude of the light-induced generator potential. Blocking of voltage-dependent Ca2+ channels did not significantly affect the magnitude of the Ca2+ signal, suggesting that the intracellular Ca2+ response arises primarily from release from intracellular stores. These results indicate that Ca2+ plays an important role in the modulation of the voltage responses to light, acting to suppress the response during repetitive or prolonged stimulation.
Muzzio
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Department of Psychology, Rutgers University, New Brunswick, NJ 08902, USA.
Talk
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Matzel
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D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D003624:Darkness; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D066298:In Vitro Techniques; D008027:Light; D008974:Mollusca; D010775:Photic Stimulation; D017956:Photoreceptor Cells, Invertebrate / Q000187:drug effects / Q000502:physiology*; D011930:Reaction Time
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002104:Cadmium; D002118:Calcium