Factors involved in the increase of K+ efflux of erythrocytes in low chloride media.

The rate constant of the Rb+(K+) efflux in isotonic NaCl solutions containing sucrose is increased when the NaCl concentration is reduced. When NaCl is replaced by Na-gluconate no change of the rate constant can be observed. The ionic strength of the solution is discussed as one factor influencing the Rb+(K+) efflux. The addition of furosemide (0.5 mM) inhibits the rate constant of the Rb+(K+) efflux in solutions of different ionic strength by about 50%. The increase of the rate constant in solutions of low ionic strength containing sucrose is interpreted as a stimulation of the chloride-dependent Na,K cotransport and the K,Cl cotransport.