Recent advances on endogenous Na+,K+-ATPase inhibitors: clinical investigation and purification

Evidence exists which demonstrates the relationship between a Natriuretic Factor or Na+,K+-ATPase inhibitor and volemic expansion, both in man and animal. Patients having extracellular volume expansion have been studied for the effect of their plasma on erythrocytes 3H-ouabain binding. High levels of ouabain-like activity was found in plasma from acromegalic patients and patients with chronic renal failure. High levels were also observed in some hypertensive patients. A partial purification of such a compound was performed from urine of hypertensives. The partially purified compound inhibited to a greater extent the Na+,K+-ATPase semi-purified from dog kidney than that from sheep brain. The present data are consistent with the possible regulation of the activity or the secretion of plasma ouabain-like activity by extracellular volume.