Norepinephrine spillover in forearm and subcutaneous adipose tissue beforeand after eating

The sympathetic nervous system regulates lipolysis. There are regional diff erences in the sensitivity of lipolysis to adrenergic regulation. Little is known about regional sympathetic activity in response to eating in humans. We studied the effect of feeding on systemic and local sympathetic nervous system activity and lipolysis in lean healthy subjects (three women and fi ve men; age, 27.0 +/- 2.0; body mass index, 23.4 +/- 1.2 kg/m(-2)) using is otope dilution methodology and arterio-venous sampling. Feeding increased a rterial norepinephrine (NE) concentration (mean premeal, 0.96 +/- 0.12 nmol /L.L; mean postmeal, 1.28 +/- 0.14 nmol/L.L; P < 0.02) and total body NE sp illover (mean premeal, 2.11 +/- 0.30 nmol/min.L; mean postmeal, 2.76 +/- 0. 31 nmol/min.L; P < 0.02), whereas the arterial epinephrine concentration de creased (mean premeal, 289 +/- 61 pmol/L; mean post-meal, 170 +/- 5 pmol/L; P < 0.02). Palmitate concentration and total body systemic rate of appeara nce of palmitate declined postprandially (mean premeal, 117 +/- 15 mu mol/m in; mean postmeal, 38 +/- 4 mu mol/min; P < 0.01). NE spillover increased b y the same proportion in both forearm and adipose tissue [in forearm, mean premeal and postmeal, 1.02 +/- 0.11 and 2.41 +/- 0.44. nmol/100 mL.min, res pectively (P < 0.02); in adipose tissue, mean premeal and postmeal, 0.41 +/ - 0.12 and 0.73 +/- 0.17 nmol/100 g.min, respectively (P < 0.02)]. The resu lts show that a meal caused differential changes in systemic sympatho-adren al activity and an increase in sympathetic activity in adipose tissue postp randially, However, this increase in postprandial sympathetic activity was not enough to overcome the inhibition of lipolysis by insulin.