Contributions of Vasopressin and Other Pressor Systems to DOC-Salt Hypertension in Rats

Abstract

The roles of arginine vasopressin (AVP), the sympathetic nervous system, and the renin-angiotensin system in maintaining elevated blood pressure in established DOC-salt hypertension in rats were studied by injection of specific antagonists of these systems. The specific AVP antagonist dPVDAVP decreased blood pressure by 19 ± 3 mm Hg in hypertensive rats and 6 ± 2 mm Hg in control rats. In a different group of rats ganglionic blockade with chlorisondamine also caused a greater decrease in blood pressure in DOC-salt rats compared to controls (99 ± 6 vs 58 ± 4 mm Hg, respectively). In rats with autonomic ganglia blocked subsequent vasopressin antagonism decreased blood pressure 29 ± 4 mm Hg in DOC-salt rats and 14 ± 2 mm Hg in control rats. Converting enzyme inhibition with captopril in rats with autonomic ganglia blocked caused a lesser decrease in blood pressure in DOC-salt rats than in controls (8 ± 2 vs 14 ± 2 mm Hg, respectively). These results indicate that both AVP and the sympathetic nervous system contribute to the maintenance of DOC-salt hypertension. The renin-angiotension system appears to be relatively less important.