Direct Free Fatty Acid Uptake Into Human Adipocytes In Vivo
Relation to Body Fat Distribution
Article Figures & Tables
Figures
- FIG. 1.
Kinetics of radiolabeled FFAs in plasma and plasma triglycerides (TG). The decay of plasma FFA radioactivity (solid lines) and appearance in plasma triglycerides (dashed lines) before and after intravenous bolus administration of [14C]FFA are shown. ○, values for women; •, values for men. In protocol 2, adipose tissue biopsies were collected 40–45 min after the bolus, a time when most of the tracer has disappeared from plasma but has not substantially entered circulating triglyceride.
- FIG. 2.
14C palmitate in the FFA fraction of whole–adipose tissue lipid. Shown is the percent of 14C in lipid extract of whole adipose tissue that was found in the FFA fraction in abdominal and femoral subcutaneous depots in women (right) and men (left) at 15 and 30 min after intravenous bolus administration of [1-14C]palmitate. Inset: Relationship between plasma FFA radioactivity at the time of the biopsy (x-axis) and the radioactivity in the fatty acid fraction of whole adipose tissue measured using TLC (y-axis) in men.
- FIG. 3.
Sex and depot differences in adipose tissue FFA tracer uptake. The lipid specific activity of abdominal and femoral adipose tissue in nonobese men and women (A) and the percent of the tracer stored in upper-body subcutaneous and lower-body fat (B). In both depots, tracer uptake is greater in women than in men. *P < 0.05, ***P < 0.001, men vs. women; §P < 0.05, upper-body subcutaneous (UBSQ) vs. leg fat.
- FIG. 4.
Sex- and depot-specific tracer uptake in adipose tissue of obese men and women after continuous tracer infusion. Specific activity of abdominal and femoral fat depots in obese men and women (A) and the percent of the tracer stored in upper-body subcutaneous (UBSQ) and lower-body fat (B). §P < 0.05, upper-body subcutaneous vs. leg fat; ***P < 0.001, men vs. women.
Tables
- TABLE 1
Characteristics of volunteers
Protocol 2 Protocol 3 Women Men P Women Men P n 12 15 12 10 Age (years) 29 ± 2 35 ± 3 0.04 38 ± 3 38 ± 2 0.95 BMI (kg/m2) 22.8 ± 0.4 23.9 ± 0.4 0.04 33.0 ± 1.0 33.4 ± 0.9 0.64 Percent fat 31 ± 1 20 ± 2 <0.0001 46 ± 2 35 ± 1 <0.0001 Total body fat (kg) 18.3 ± 0.7 15.6 ± 1.6 0.11 40.8 ± 2.4 35.5 ± 2.5 0.14 Leg fat (kg) 7.7 ± 0.5 5.4 ± 0.4 0.002 15.9 ± 1.3 11.5 ± 0.9 0.009 Upper-body subcutaneous fat (kg) 10.4 ± 0.6 8.9 ± 1.3 0.24 21.0 ± 1.2 17.9 ± 1.3 0.10 Visceral fat (kg) 1.2 ± 0.3 1.0 ± 0.3 0.60 4.0 ± 0.4 6.1 ± 0.7 0.02 Abdominal fat cell size (μg lipid/cell) 0.411 ± 0.036 0.443 ± 0.049 0.51 0.858 ± 0.073 0.750 ± 0.048 0.24 Femoral fat cell size (μg lipid/cell) 0.481 ± 0.027 0.411 ± 0.029 0.11 0.813 ± 0.082 0.801 ± 0.071 0.91 Data are mean ± SE.
- TABLE 2
Fatty acid transporter gene expression
Women Men Abdomen Thigh Abdomen Thigh CD36 2.51 ± 0.51 2.74 ± 0.64* 2.42 ± 0.48 2.17 ± 0.35 FATP1 1.85 ± 0.54 1.71 ± 0.46 2.12 ± 0.42 1.74 ± 0.36 FATP4 1.48 ± 0.56 1.55 ± 0.30* 1.40 ± 0.29 1.26 ± 0. 20 Average 2.51 ± 0.51 2.00 ± 0.42 1.98 ± 0.26 1.72 ± 0.24† Data are mean ± 1 SD for gene expression relative to a calibrator sample. Abdominal and thigh samples from 12 normal-weight women and 7 normal-weight men were analyzed.
- *
* P < 0.05 vs. thigh for men;
- †
† P < 0.05 vs. abdomen.
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