Rhodopsin: Responses from Transient Intermediates Formed during Its Bleaching

Abstract

Fast electrical responses elicited from the transient intermediates in the bleaching of rhodopsin have been investigated in the retina of the albino rat. In the experiments we used two-flash stimuli triggered sequentially with a continuously variable time delay between them. At room temperature the potential is biphasic in wave-form. The dominant, corneal-positive component is preceded by a small, corneal-negative component. Cooling the retina to about 0°C suppresses the positive component and isolates the faster, negative component. Experiments with color filters show that these two components display different spectral sensitivities and, hence, suggest that each of them is produced by a different photoproduct of bleaching.