Racial differences in lipid metabolism in women with abdominal obesity

We evaluated palmitate rate of appearance (R-a) in plasma during basal cond itions and during a four-stage epinephrine infusion plus pancreatic hormona l clamp in nine white and nine black women with abdominal obesity, who were matched on fat-free mass, total and percent body fat, and waist-to-hip cir cumference ratio. On the basis of single-slice magnetic resonance imaging a nalysis, black women had the same amount of subcutaneous abdominal fat but less intra-abdominal fat than white women (68 +/- 9 vs. 170 +/- 14 cm(2), P < 0.05). Basal palmitate R-a was lower in black than in white women (1.95 +/- 0.26 vs. 2.88 +/- 0.23 mu mol . kg fat-free mass(-1) . min(-1), P < 0.0 05), even though plasma insulin and catecholamine concentrations were the s ame in both groups. Palmitate R-a across a physiological range of plasma ep inephrine concentrations remained lower in black women, because the increas e in palmitate R-a during epinephrine infusion was the same in both groups. We conclude that basal and epinephrine-stimulated palmitate R-a is lower i n black than in white women with abdominal obesity. The differences in basa l palmitate kinetics are not caused by alterations in plasma insulin or cat echolamine concentrations or lipolytic sensitivity to epinephrine. The lowe r rate of whole body fatty acid flux and smaller intra-abdominal fat mass m ay have clinical benefits because of the relationship between excessive fat ty acid availability and metabolic diseases.