MUSCLE SYMPATHETIC NERVOUS-SYSTEM ACTIVITY IN BLACK AND CAUCASIAN HYPERTENSIVE SUBJECTS

Objective: To compare muscle sympathetic nerve activity (MSNA) in age- and weight-matched African-Americans and American Caucasians with pri mary hypertension. Design: Using microneurography, we compared MSNA at rest and in response to cold-presser testing and handgrip exercise in 13 hypertensive African-Americans and 12 hypertensive American Caucas ians. Methods: All subjects were withdrawn from antihypertensive medic ations for at least 2 weeks before the study. MSNA was recorded from t he left peroneal nerve. Results: Resting MSNA was similar in the Black s and the Caucasians. Increases in muscle efferent activity, mean arte rial pressure and heart rate in response to the cold pressure and hand grip exercise were not significantly different in Black and in Caucasi an subjects. Conclusion: MSNA, either at rest or in response to certai n laboratory stressors, is not different in Black and in Caucasian hyp ertensive subjects with similar resting blood pressures.