Angiotensin II-induced effects on adipose and skeletal muscle tissue blood flow and lipolysis in normal-weight and obese subjects

The present study was designed to investigate the effects of angiotensin II (Ang II) on adipose and skeletal muscle tissue blood flow and lipolysis in normal-weight and obese subjects using the microdialysis technique. Microdialysis probes were placed in the abdominal sc adipose tissue left and right from the umbilicus and in the gastrocnemius muscle of both legs in eight normal-weight and eight obese men. Probes were consecutively perfused with 1.0 nM Ang II, 1.0 microM Ang II, and 1.0 microM Ang II + 48 microM hydralazine or with Ringer solution (control). Ethanol and glycerol concentrations in the dialysate were measured as an indicator of local blood flow and lipolysis, respectively. Ang II caused an increase in ethanol outflow/inflow ratio, compared with baseline values both in adipose tissue (average of both groups, Ang 1.0 nM: 0.03 +/- 0.01, P = 0.02; Ang 1.0 microM: 0.05 +/- 0.01, P < 0.01) and muscle (average of both groups, Ang 1.0 nM: 0.02 +/- 0.01, P = 0.09; Ang 1.0 microM: 0.04 +/- 0.01, P = 0.01), indicating a decrease in local blood flow. These effects were not significantly different in obese and normal-weight subjects. The decrease in local blood flow was accompanied by unchanged interstitial glycerol concentrations in adipose tissue (except during the supraphysiological dose) and skeletal muscle, suggesting that Ang II inhibits lipolysis in both tissues. Thus, the present data suggest that Ang II decreases local blood flow in a dose-dependent manner and inhibits lipolysis both in adipose and skeletal muscle tissue. These effects were not significantly different in obese and normal-weight subjects in both tissues.