Reconstruction of the slow PIII from the rod potential.

Light-induced changes in K+ efflux across the photoreceptor membrane are compensated for by active uptake of K+ by a pump, which works with a time lag causing changes in [K+]o termed the KRG. From aspartate-treated bullfrog retinas we isolated the rod potential and the slow PIII, and by using them as indices of rod function and the KRG, respectively, studied relationships between the two. We conclude in support of our previous study that in rods the pump for K+ uptake works with a time lag of some 9 sec in time constant.