Experimental verification of an expected relation between time of incubation and magnitude of the fast and slow fractions of the sodium efflux from amphibian eggs.

The Na+ efflux curves of single ovarian eggs are separable into two fractions. The magnitude of the slow fraction increases slowly with time of exposure of the eggs to labeled Na+, long after the fast fraction has reached equilibrium. The data agree with the theory that the fast fraction is rate-limited by surface permeation and that the slow fraction is rate-limited by desorption from intracellular adsorption sites.