Background: African Americans have a high prevalence of hypertension and hypertension-related vascular disease. We previously reported that plasma aldosterone concentrations are relatively high in hypertensive African Americans. This study evaluates the hypothesis that hypertension and hypertension-related alterations of peripheral vascular and renal vascular function are associated with aldosterone.
Methods: Twenty four-hour blood pressures, cardiac output, renal blood flow (RBF), plasma renin activity (PRA), and plasma aldosterone were measured in hypertensive and normotensive African Americans. Hemodynamic measurements were repeated in response to graded infusions of norepinephrine (NE).
Results: Ambulatory blood pressures in hypertensives and normotensives were 142 +/- 1/86 +/- 1 and 117 +/- 1/70 +/- 1 mm Hg, respectively. Cardiac index (CI) was lower (P < 0.01), peripheral vascular resistance was higher (P < 0.0001), arterial compliance was lower (P < 0.0001), RBF was lower (P = 0.04), and renal vascular resistance (RVR) was higher (P < 0.0001) in the hypertensives. Overall, blood pressures were positively correlated with peripheral vascular resistance (P < 0.0001) and inversely correlated with vascular compliance (P < 0.0001). In response to NE, hypertensives had greater increases of systolic blood pressure (P < 0.004) and pulse pressure (P < 0.005). PRA was lower (P < 0.0001) and plasma aldosterone was higher (P < 0.0001) in the hypertensives. Overall, blood pressures and pulse pressure were correlated with aldosterone (P < or = 0.01). Vascular compliance, RVR, and the increment of RVR in response to NE were also correlated with aldosterone (P < or = 0.03).
Conclusions: Aldosterone may contribute to hypertension and to hypertension-related alterations of peripheral vascular and renal vascular function in African Americans.