The membrane locus of Ca-stimulated K transport in energy depleted human red blood cells.

Energy depleted human red cells subsequently exposed to iodoacetate (IAA) develop, upon the addition of Ca, a marked increase in K permeability, while Na permeability is unaltered. The kinetic characteristics of this augmented K permeability indicate that the transport process is membrane mediated. Thus, the inward and outward rate constants for K increase as the concentration of external K is increased reaching maximum values between 2 to 5MM; further increases in external K results in a partial reduction of the rate constants.