Muscle sympathetic nerve activity and hemodynamic alterations in middle-aged obese women

To study the relationship between the sympathetic nerve activity and hemody namic alterations in obesity, we simultaneously measured muscle sympathetic nerve activity (MSNA), blood pressure, and forearm blood flow (FBF) in obe se and lean individuals. Fifteen normotensive obese women (BMI = 32.5 +/- 0 .5 kg/m(2)) and 11 age-matched normotensive lean women (BMI = 22.7 +/- 1.0 kg/m(2)) were studied, MSNA was evaluated directly from the peroneal nerve by microneurography, FBF was measured by venous occlusion plethysmography, and blood pressure was measured noninvasively by an autonomic blood pressur e cuff. MSNA was significantly increased in obese women when compared with lean control women. Forearm vascular resistance and blood pressure were sig nificantly higher in obese women than in lean women. FBF was significantly lower in obese women. BMI was directly and significantly correlated with MS NA, blood pressure, and forearm vascular resistance levels, but inversely a nd significantly correlated with FBF levels. Obesity increases sympathetic nerve activity; and muscle vascular resistance, and reduces muscle blood fl ow. These alterations, taken together, may explain the higher blood pressur e levels in obese women when compared with lean age-matched women.