Lactate and Glycerol Release from the Subcutaneous Adipose Tissue of Obese Urban Women from South Africa; Important Metabolic Implications1

Abstract

Interstitial glycerol and lactate production was measured in the s.c. adipose tissue of two anatomical regions in 10 obese urban black women (BW) and 10 obese urban white women (WW) matched for age, body mass index, waist-hip ratio, diet, and physical activity. This was done with the s.c. microdialysis technique and combined with adipose tissue blood flow (ATBF) rates calculated from 133Xe clearance. Biochemical measurements were done in the postabsorptive and postprandial state. Bioimpedance and computed tomography scans were used for analyses of body composition. BW responded with lower plasma insulin levels, but higher glucose levels, during the oral glucose tolerance test. BW have higher lactate release from the s.c. adipose tissue, compared with WW, in the postabsorptive state (abdominal: 7.8 +/- 0.9 vs. 2.4 +/- 0.3 micromol/kg x min, P < 0.0001; femoral: 9.1 +/- 0.9 vs. 2.1 +/- 0.3 micromol/kg x min, P < 0.0001) and during the postprandial period (at 1 h, abdominal = 7.3 +/- 0.8 vs. 3.0 +/- 0.4 micromol/kg x min, P < 0.0001, femoral area = 8.1 +/- 1.0 vs. 2.7 +/- 0.4 micromol/kg x min, P < 0.0001; at 2 h, abdominal = 5.7 +/- 0.4 vs. 3.1 +/- 0.3 micromol/kg x min, P < 0.001). The BW also released more glycerol from the sc adipose tissue in the postabsorptive state (abdominal = 1.15 +/- 0.17 vs. 0.65 +/- 0.03 micromol/ kg x min, P < 0.009; femoral = 1.55 +/- 0.19 vs. 0.72 +/- 0.05 micromol/kg x min, P < 0.001) and during the postprandial period (at 1 h, abdominal = 1.05 +/- 0.15 vs. 0.11 +/- 0.02 micromol/kg x min, P < 0.001, femoral = 1.05 +/- 0.12 vs. 0.21 +/- 0.03 micromol/kg x min, P < 0.001; at 2 h, abdominal = 0.31 +/- 0.06 vs. 0.04 +/- 0.01 micromol/kg x min, P < 0.001, femoral = 0.28 +/- 0.07 vs. 0.05 +/- 0.01 micromol/kg x min, P < 0.003). Postprandially, the BW had higher ATBF rates in the abdominal and femoral areas. WW have more visceral fat (150 +/- 2.0 vs. 110 +/- 5.0 cm2, P < 0.05). In conclusion, the insulinopenic BW have a brisker lipolysis and ATBF and release more glycerol and lactate from their sc adipose tissue, both in the postabsorptive state and after an oral glucose tolerance test. These variations in adipose tissue metabolism may contribute to differences observed in the disease profiles of these two groups of women.