Demonstration of a humoral inhibitor of the Na+-K+ pump in some models of experimental hypertension.

We have previously shown that ouabaln-sensitive Rb uptake, a measure of Na-K pump activity, is decreased in the blood vessels of dogs with one-kidney, one wrapped hypertension and rats with onekidney, DOCA, saline hypertension. We here extend the study to rats with one-kidney, one clip and reduced renal mass-saline hypertension. We also assayed supernates of boiled plasma from three of these models for ouabain-sensitive Rb uptake suppressing activity. Finally, we examined the influence of the anteroventral third ventricle (AV3V) lesion in the rat on vascular pump and plasma supernate activities. We found that ouabain-sensitive Rb uptake is suppressed in the tail arteries of rats with one-kidney, one clip and reduced renal mass hypertension and that plasma supernates from these rats and from dogs with one-kidney, one wrapped hypertension suppress Rb uptake when applied to tail arteries from normal rats. We also found that, in the volume-expanded state, rats with AV3V lesions had higher vascular ouabain-sensitive Rb uptake than rats with sham lesions and evidence for decreased inhibitory activity of the plasma. These findings suggest that reduced vascular Na-K pump activity is common to several models of experimental hypertension and that this defect results from a heat-stable ouabain-like agent in plasma that originates in or is influenced by the AV3V area of the brain. (Hypertension 3 (suppl II): II-96-II-101, 1981)