CREATINE-KINASE IS REQUIRED FOR SWELLING-ACTIVATED K-CL COTRANSPORT IN DOG RED-BLOOD-CELLS

K-Cl cotransport in resealed dog red cell ghosts requires the incorpor ation of creatine phosphate before resealing; incorporation of ATP has no effect [Colclasure and Parker. Am. J. Physiol. 265 (Cell Physiol. 34): C1648-C1652, 1993]. A role for creatine kinase (CK) in swelling-a ctivated K-Cl cotransport was investigated. 2,4-Dinitrofluorobenzene ( DNFB), an inhibitor of CK, inhibited K-Cl cotransport in intact red bl ood cells and resealed ghosts from DNFB-treated cells. Incorporation o f exogenous CK into ghosts of DNFB-treated cells restored K-CI cotrans port. Therefore DNFB inhibits CK and not the cotransporter. Inhibition of native CK in ghosts by DNFB and the incorporation of CK into the g hosts were demonstrated in electrophoretic gels. In a dose-response ex periment, similar to 770 molecules CK/ghost restored 50% of control co transport. Since creatine phosphate is a substrate only for CK, CK pro vides ATP to a site inaccessible to cytoplasmic ATP. The nature of thi s site and its role in K-Cl cotransport are uncertain, but an essentia l function for CK is established.