Ethnic differences in blood pressure with observations on noradrenaline and renin. A hospital hypertensive population.

100 patients with essential hypertension (77 whites, 23 black) were studied with measurements of plasma noradrenaline concentration and plasma renin activity. Black patients had higher blood pressure than whites. There were no ethnic differences in mean plasma noradrenaline, but plasma renin activity was lower in blacks than whites, and this difference was not related to differences in sodium intake. Plasma noradrenaline increased with age in blacks, and in a white control group. Young white hypertensive patients (< 45 years) had higher plasma noradrenaline than controls, and in white hypertensives plasma noradrenaline was positively correlated with plasma renin.