Kinetic studies on the calcium-dependent potassium transport in human red blood cells

The kinetics of the Ca-dependent K transport across the human red cell membrane were studied under experimental conditions allowing the separation of this step from the previous membrane events. Net potassium and tracer potassium fluxes were measured and a self-consistent model was constructed for calculating the ionic permeability values. All the experimental results could be interpreted by means of a nonsaturable neutral K selective channel. In net K efflux measurements the accompanying C1 movement was found to be rate-limiting, and the charge-carrying C1 permeability of the red cell membrane could be calculated.