The effect of cellular calcium on Na+/K+ cotransport in human red blood cells

The increase in Ca2+ permeability by addition of ionophore A23187 in the presence of external Ca2+ did not alter the bumetanide-sensitive Na+/K+ effluxes in human red blood cells. An inhibition of this pathway by cellular Ca2+ could be observed only under conditions in which the cellular ATP content was drastically depleted.