| Popis: |
This study examined the postprandial lipemia of two groups of men displaying similar age, body weight, and regional fat distribution, but characterized by either low (n = 11) or high (n = 15) α2-adrenergic sensitivity of subcutaneous abdominal adipocytes. In addition to fat cell lipolysis, adipose tissue lipoprotein lipase (AT-LPL) as well as postheparin plasma LPL activities were measured in the fasting state. Fasting AT-LPL and PH-LPL activities were similar in both groups. Maximal adipose cell lipolysis induced by isoproterenol (β-adrenergic agonist) as well as the β-adrenergic sensitivity did not differ between both groups of men. The selective α2-adrenergic agonist UK-14304 promoted a similar antilipolytic response in subcutaneous abdominal adipocytes from both groups. However, the α2-adrenergic sensitivity, defined as the dose of UK-14304 that produced half-maximal inhibition of lipolysis (IC50), was significantly different between groups (P < 0.0001). Men with low versus high subcutaneous abdominal fat cell α2-adrenergic sensitivity showed higher fasting TG levels. In the whole group, a positive relationship was observed between log-transformed IC50 UK-14304 values of subcutaneous adipocytes and fasting TG levels (r = 0.39, P < 0.05), suggesting that a low abdominal adipose cell α2-adrenergic sensitivity is associated with high TG levels. After the consumption of a high-fat meal, subjects with low subcutaneous abdominal adipose cell α2-adrenergic sensitivity showed higher TG levels in total, medium, and small triglyceride-rich lipoprotein (TRL) fractions at 0- to 6-h time points than men with high adipocyte α2-adrenergic sensitivity (P values ranging from 0.01 to 0.05). Stepwise regression analysis showed that the fasting TG concentration was the only variable retained as a significant predictor of the area under the curve of TG levels in total TRL fractions (73% of variance) among independent variables such as body weight, percent body fat, visceral and subcutaneous abdominal adipose tissue accumulation measured by CT, as well as subcutaneous abdominal fat cell α2-adrenoceptor sensitivity. Taken together, these results indicate that a reduced antilipolytic sensitivity of subcutaneous abdominal adipocytes to catecholamines may increase fasting TG levels, which in turn play a role in the etiology of an impaired postprandial TRL clearance in men. —Imbeault, P., C. Couillard, A. Tremblay, J-P. Després, and P. Mauriège. Reduced α2-adrenergic sensitivity of subcutaneous abdominal adipocytes as a modulator of fasting and postprandial triglyceride levels in men. J. Lipid Res. 2000. 41: 1367–1375. |
