Importance of Plasma Renin Activity Suppression and Venous Distensibility on Pressor and Natriuretic Responses to Intravenous Salt Load in Borderline Hypertension

Abstract

Cardiopulmonary receptors influence renin release in a variety of physiological situations and in a fashion related to the degree of peripheral venous distensibility. We studied two groups of borderline hypertensives (BHTs) with different capacities to suppress plasma renin activity in response to saline infusion (0.20 mL/kg/per minute for 2 hours). Those BHTs with low suppressive capacity (L-supp) showed an increased venous distensibility in comparison with those with high suppressive capacity (H-supp). Saline infusion led to a significant increase in blood pressure only in L-supp BHTs, which was associated with enhanced 24-hour postloading natriuresis and raised plasma levels of an Na/K ATPase inhibitor (+12.2%). This result underlines the importance of venous distensibility as a determinant of pressor and humoral response to acute volume expansion.