Effect of exercise training on in vivo lipolysis in intra-abdominal adipose tissue in rats

Intra-abdominal obesity is associated with cardiovascular disease and nonin sulin-dependent diabetes mellitus, and physical training has been suggested to alleviate these conditions. We compared epinephrine-stimulated lipolysi s in vivo in three intra-abdominal adipose tissues (ATs: retroperitoneal, p arametrial, and mesenteric) and in subcutaneous AT, and we also studied the effect of physical training. Moreover, we studied the effect of physical t raining on epinephrine-stimulated lipolysis in muscle in vivo. Female rats were either swim trained (15 wk, n = 8) or sedentary (n = 7). Under anesthe sia, a two-stage intravenous epinephrine infusion (60 min of 80 and 200 ng . kg(-1).min(-1), respectively) was carried out, and local interstitial gly cerol concentration was measured by the microdialysis technique. Blood flow was measured by microspheres. Training increased blood flow in all ATs [on average: 73 +/- 12 (trained) vs. 14 +/- 4 (sedentary) ml.100g(-1).min(-1), P< 0.05]; nevertheless, epinephrine-stimulated interstitial glycerol conce ntrations were increased or unchanged. Interstitial glycerol concentration was higher in intra-abdominal than in subcutaneous AT in both trained and s edentary rats. In skeletal muscle, interstitial glycerol concentration and blood flow did not differ between trained and sedentary rats. In conclusion , in vivo lipolysis is higher both in the basal state and during epinephrin e-stimulation in intraabdominal than in subcutaneous AT, and training may b e beneficial in alleviating intra-abdominal obesity by enhancing lipolysis in intra-abdominal fat depots.