Lactate and glycerol release from subcutaneous adipose tissue in black andwhite lean men

To measure interstitial glycerol and lactate production from the sc adipose tissue of two regions in nine black and nine white lean men, sc microdialy sis was performed in combination with adipose tissue blood flow rates measu red with Xe-133 clearance. In the postabsorptive state, the plasma glucose and insulin levels of the b lack men and white men were similar. The black men had higher plasma free f atty acids (825 +/- 97 vs. 439 +/- 58 mu mol/L; P < 0.005), glycerol (99.5 +/- 5.1 vs. 54.1 +/- 3.3 mu mol/L; P < 0.0001), and lactate (1056 +/- 95 vs . 729 +/- 45 mu mol/L; P < 0.01). Interstitial glycerol concentrations in t he black and white men were 227 vs. 163 mu mol/L (P < 0.01) and 230 vs. 162 mu mol/L (P < 0.05) in the abdominal and femoral regions. The adipose tiss ue blood flow rate was higher in the black men in the abdominal (7.9 +/- 0. 9 vs. 3.1 +/- 0.5 mL/100 g.min; P < 0.01) and femoral area (5.2 +/- 0.6 vs. 2.8 +/- 0.3; P < 0.01). Interstitial lactate concentrations in black and w hite men were 1976 vs. 1364 mu mol/L (P < 0.004) and 1953 vs. 1321 mu mol/L (P < 0.004) in the abdominal and femoral regions, respectively. Glycerol r elease was higher in black men vs. white men for abdominal (0.21 +/- 0.02 v s. 0.14 +/- 0.02 mu mol/100 g.min; P < 0.02) and femoral (0.22 +/- 0.02 vs. 0.15 +/- 0.01; P < 0.05) areas. Postprandially, black men had higher plasma glucose levels [1 h, 9.6 +/- 0. 4 vs. 8.2 +/- 0.5 mmol/L (P < 0.05); 2 h, 8.9 +/- 0.4 vs. 7.2 +/- 0.4 mmol/ L (P < 0.01)], but lower plasma insulin levels [1 h, 173 +/- 13 vs. 264 +/- 48 pmol/L (P < 0.05); 2 h, 136 +/- 20 vs. 209 +/- 34 pmol/L (P < 0.05)]. P lasma free fatty acid, lactate, and glycerol levels remained higher in the black men. After 1 h, lactate release was higher in the black men vs. that in the white men for abdominal (20.5 +/- 1.6 vs. 14.7 +/- 2.5 mu mol/100 g. min; P < 0.05) and femoral (15.6 +/- 1.1 vs. 12.1 +/- 1.8; P < 0.03) areas. We conclude that the black men, who are relatively insulinopenic postprandi ally, have a brisker lipolysis and also release more lactate from sc fat ti ssue than white men. These differences in adipose tissue metabolism mag be related to differences in the lipid profiles and glucose metabolism previou sly documented in these ethnic groups.