Effects of removing extracellular Ca2+ on excitation and adaptation in Limulus ventral photoreceptors.
In Limulus ventral photoreceptors, removing extracellular calcium (Ca2+o) increases the median latency of light-evoked discrete waves. Removal greatly lengthens the time-to-peak of responses in the dark-adapted cell, but not in the light-adapted cell. Removal does not block light-adaptation or the light-induced rise in intracellular calcium (Ca2+i). These results are interpreted in terms of the hypothesis that both sensitivity and the kinetics of excitation are dependent on Ca2+i, and that Ca2+i is dependent on Ca2+o in the dark-adapted cell, but in the light is dependent largely on Ca2+ released from intracellular compartments.
D000221:Adaptation, Ocular; D000818:Animals; D002118:Calcium / Q000502:physiology*; D003623:Dark Adaptation; D006737:Horseshoe Crabs; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000502:physiology*; D011930:Reaction Time
D002118:Calcium