Inhibition of (Na+K+)-ATPase and cation transport by an antibody against renal plasma membranes.

An antibody was raised in rabbits against NaI extracted plasma membranes of rat kidney. The antibody inhibited (Na+K+)-ATPase of basolateral membranes and of rat erythrocyte ghosts. Also K+-stimulated pNPase was inhibited. No effect on Mg-ATPase and basal pNPase activity was registered. Kinetic experiments with Na+,K+ and Mg-ATP showed a noncompetitive inhibition of (Na+K+)-ATPase by the antibody. Hill constants were unchanged. In renal epithelial cell cultures as well as in intact rat erythrocytes ouabain sensitive 22Na-efflux and 42K influx was inhibited by the antibody. It is concluded that outward facing Na+K+-ATPase is immunogenic. The antibody can be raised when the antigen is adequately disintegrated to open otherwise hidden antigenic sites.