GLYCEROL PRODUCTION IN SUBCUTANEOUS ADIPOSE-TISSUE IN LEAN AND OBESE HUMANS

To estimate the regional subcutaneous glycerol production rate in normal and obese humans, the venous arterialized plasma glycerol, interstitial glycerol in the subcutaneous adipose tissue together with adipose tissue blood flow (ATBF, ml/100 g.min) were measured in the Postabsorptive state and for 2 h after ingestion of 100 g of oral glucose. Eight lean and eight obese men with normal oral glucose tolerance tests were investigated with the subcutaneous microdialysis technique and Xe-133 clearance. In the postabsorptive state, the interstitial glycerol concentrations in lean and obese subjects were 170 +/- 21 vs. 282 +/- 28 mu-M (P < 0.01) and 156 +/- 23 vs. 225 +/- 12-mu-M (P < 0.05) in the abdominal and femoral subcutaneous adipose tissue, respectively. The corresponding arterial glycerol levels were 54 +/- 4 vs. 75 +/- 14-mu-M (NS). Abdominal ATBF was greater in lean subjects (3.2 +/- 0.6 vs. 1.6 +/- 0.3; P < 0.05), whereas femoral ATBF was similar in both groups (2.7 +/- 0.4 vs. 2.4 +/- 0.7). Estimated mean local glycerol release (mu-mol/100 g.min) was similar in the lean and obese group (0.16 +/- 0.03 vs. 0.20 +/- 0.05 and 0.18 +/- 0.02 vs. 0.17 +/- 0.04) in the abdominal and femoral site, respectively. We conclude that glycerol production from the subcutaneous tissue is increased in obesity, irrespective of adipose tissue distribution. This enhancement is due to the increased adipose tissue mass.