Studies on visual transduction in the retinal rods of the frog

In recent theories of visual transduction, an active form of rhodopsin plays a decisive role. If metarhodopsin II is considered to be a likely candidate for this role, its properties and reactions are of interest. A scheme describes how the various metarhodopsins react with each other. In the electrophysiological experiments, the dark currents and the photocurrents generated by the plasma membrane of the outer segments are analyzed. While the dark currents are computed from voltage gradients and the interstitial resistance in the receptor layer, the photocurrents are directly from single cells under voltage-clamp conditions.