Black women have one of the highest prevalence rates of
hypertension and
obesity in the United States. We previously reported that sympathetic activation induced by
obesity is a significant contributor to
hypertension in white patients. It is unknown whether sympathetic activity similarly contributes to
hypertension in obese black women.
METHODS AND RESULTS: We studied 42 obese women (16 white, body mass index 36±4 kg/m2, 44% with
hypertension; 26 black, body mass index 35±4 kg/m2, 46% with
hypertension).
Antihypertensive medications were discontinued for 2 weeks before the day of the study. All patients underwent complete autonomic blockade with
trimethaphan at a dosage of 4 mg/min. Resting sympathetic activity determined from muscle sympathetic nerve recordings was similar between obese black women with
hypertension and those with normotension. In whites, sympathetic activity was elevated in obese patients with
hypertension compared with normotension; the decrease in mean arterial blood pressure produced by
trimethaphan was greater in obese white patients with
hypertension compared with those with normotension (-26.8±9.7 mm Hg versus -14.8±7.9 mm Hg, P=0.02). In contrast, there was no difference in the depressor responses induced by
trimethaphan between obese black women with
hypertension and those with normotension (-15.5±10.5 mm Hg versus -12.3±10.2 mm Hg, P=0.45). Mean arterial blood pressure remained elevated in obese blacks with
hypertension compared with those with normotension during
trimethaphan infusion (83.7±15.0 mm Hg versus 71.7±9.8 mm Hg, P=0.02). Heart rate increased similarly with
trimethaphan between white (P=0.11) and black (P=0.76) women with
hypertension and normotension.
CONCLUSIONS: