ATP dependence of K-Cl cotransport in dog red blood cells

Swelling-induced K-Cl cotransport in resealed dog red blood cell ghosts requires the presence of an ATP-generating system (G. C. Colclasure and J. C. Parker. J. Gen. Physiol. 100: 1-10, 1992). The present study shows that the endogenous adenine nucleotide present in the dog ghosts is sufficient to activate K-Cl cotransport, provided that creatine phosphate is incorporated in them. Creatine kinase is not required, because dog red blood cells, unlike those of humans, possess this enzyme. Although some ATP appears to be required for K-Cl cotransport by dog ghosts, an excess of this nucleotide is inhibitory. Creatine phosphate appears to play a special role in generating the ATP required for activation of K-Cl cotransport. If ghost ATP content is manipulated in the absence of creatine phosphate, by simply adding ATP to the hemolysate, no stimulation of K-Cl cotransport occurs. On the other hand, when creatine phosphate is present, K-Cl cotransport is activated. The results are discussed in relation to current views regarding the role of ATP in activation of K-Cl cotransport and the concept of the "phosphocreatine shuttle."