On the ATP dependence of the Ca-induced increase in K permeability observed in human red cells

When red cells are starved or incubated in the presence of metabolic poisons, with or without substrates, a large increase in K⁺ permeability is observed which depends on the presence of Ca²⁺ in the medium. The production or removal of a metabolite which controls the K⁺ permeability has been proposed to explain these effects. In the present experiments, a parallelism is found to exist between the rate of ATP depletion and the increase in Ca²⁺ uptake and K⁺ loss when red cells are depleted by different methods. The results support the view that the intracellular concentration of ATP may be the main factor on which the rate of Ca²⁺ uptake and the subsequent increase in K⁺ permeability depend.