Abstract
The metabolic inhibitor, iodoacetic acid (IAA), has commonly been used to increase Ca-dependent K efflux in red blood cells. It is thought that this effect of IAA involves the irreversible inhibition of glyceraldehyde-phosphate dehydrogenase (EC 1.2.1.12), resulting in the energy depletion of the cell. Without energy, active transport stops, and the K loss is enhanced both by increasing cellular Ca and by preventing K reuptake. The present study shows that in addition to this metabolic effect, which increases Ca-dependent K efflux, IAA also inhibits this efflux. This inhibition is irreversible and is not related to the ATP or Ca concentrations of the cells. The carboxymethylation of a specific protein band correlates with IAA inhibition of K efflux.