[Sodium specificity of the effect of cyclic nucleotides on the conductance of cytoplasmic membranes of the photoreceptor].

The effect of cyclic nucleotides (3',5'-cAMP and 3',5'-cGMP) on the membrane of the retina rod outer segment under intracellular dialysis conditions was shown to possess sodium specificity, its value in the medium with normal Na+ content being 4-20 times above that in sodium free solution. The results obtained permit a conclusion that the effect observed is due to the increased conductance of the cytoplasmic membrane of the outer segment and support the assumption concerning the mediator role of cyclic nucleotides in the photoreceptor act.