Kinetics of 42K and 86Rb loss from the crayfish retina in the dark and the effect of light on the rate of isotope loss.

86Rb and 42K loss from non-illuminated crayfish retinas is described by a sum of two exponential functions with rate constants lambda1 approximately 0.12 min-1 and lambda 2 approximately 0.006 min-1. 86Rb and 42K movements distinguish mainly by the lambda2 rate constants, lambda2Rb/lambda2K = 0.7. Oubain causes a delayed increase in the rate of isotope loss from non-illuminated retinas (lambda approximately 0.009 min-1 after 40 min). Light stimuli evoke a temporary increase in the rate of both 86Rb and 42K loss by the same factor (2.7 under these conditions). In the presence of ouabain the light-induced isotope loss is abolished after 40 min if the retina is periodically illuminated but not if the retina is kept in the dark.