[(Na+ -K+) dependent adenosine triphosphate of the small intestine: determination and properties in the rat].

A method to assay (Na+-K+) dependent ATPase is described. ADP produced is determined by the pyruvate kinase -- lactate deshydrogenase system. The method is adapted on an LKB 8,600 apparatus. This method is more reproducible, more sensitive and less time consuming than Baginski's procedure. The results given by the two methods have been compared. The stimulation by NH4+, inhibiting capacity and kinetic of inhibition by different cardiotonics have been determined on intestinal brush borders.