Light modulates voltage-dependent potassium channels in limulus ventral photoreceptors

Voltage-dependent outward current measured in the dark is reduced after illumination. This reduction can be blocked by tetraethylammonium and is associated with a decrease in total membrane conductance. The voltage dependence of the current reduced by light is the same as that of the delayed rectifier. These results indicate that light modulates the delayed rectifier. This modulation serves to maintain a stable voltage response to constant illumination.