[(NA++K+)-ATPase inhibitor from bovine hypothalamus].

The presence of an endogenous ouabain-like substance in bovine hypothalamus is demonstrated on the bas is of the ability of acid acetone extracts of hypothalamus to inhibit (NA+ + K+)-ATPase activity, 86Rb uptake, 22Na efflux and (3H)ouabain binding. Partial purification of the substance was achieved by acetic acid fractionation followed by sephadex-G25 chromatography and subsequent desalting by mixed-bed resin. The results are discussed with relation to the important role of the sodium pump inhibitor in the regulation of (N+ + K+)-ATPase activity and sodium transport and hence in the pathophysiologic mechanisms of essential hypertension.