AJP - Cell Physiology, Vol 265, Issue 6 C1648-C1652, Copyright © 1993 by American Physiological Society
ATP dependence of K-Cl cotransport in dog red blood cells
G. C. Colclasure and J. C. Parker
Department of Medicine, University of North Carolina at Chapel Hill 27699-7035.
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."
