Generation of currents accompanying the off-response of the photoreceptors in the isolated frog retina.
A prolonged weak illumination has been reported to induce an off-response in transretinal potential of bullfrog retina immersed in a low Ca2+, Ba2+ and Na-aspartate-containing solution. Changes in the interstitial current accompanying the generation of the off-response were studied by inserting a pair of micropipettes into the bullfrog retina. A transient increase in proximal-to-distal current above the dark level was observed when the off-response was developing (off-current). The current divergence of the off-current indicated that the source of the off-current was located about 75 micron below the receptor surface. In the absence of Ba2+, similar changes in currents were also observed, although no detectable off-response was observed in the transretinal potential. Findings suggest that regardless of the presence of Ba2+, current flowing outward through the plasma membrane of the rod inner segments increases transiently when the off-response is developing.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D003623:Dark Adaptation; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000502:physiology*; D011892:Rana catesbeiana
D001464:Barium; D002118:Calcium