REGIONAL DIFFERENCES IN ADIPOSE-TISSUE LIPOLYSIS FROM LEAN AND OBESE WOMEN - EXISTENCE OF POSTRECEPTOR ALTERATIONS

Lipolysis studies were performed on isolated adipose cells obtained fr om two subcutaneous regions (abdominal and femoral) in 26 premenopausa l women (16 obese and 10 lean subjects). Because obese adipocytes from both sites were significantly larger than lean fat cells, glycerol re lease measured by an ultrasensitive bioluminescent method was correcte d for variation in cell surface area. Epinephrine induced antilipolysi s at low concentrations and a net lipolytic response at higher doses, regardless of the subjects' fatness and the anatomic location of fat. However, the catecholamine and the selective alpha(2)-adrenergic agoni st, UK-14304, promoted a greater maximal antilipolytic response in bot h femoral and subcutaneous abdominal adipose cells from obese individu als than from lean individuals. Epinephrine- and UK-14304-induced maxi mal antilipolysis of femoral adipocytes was also positively associated with indicators of total adiposity. On the other hand, the maximal li polytic responses to postadrenoceptor agents such as dibutyryl adenosi ne 3',5'-cyclic monophosphate, forskolin, and theophylline were lower in both adipose regions in obese than in lean women. Femoral fat cell lipolysis in the presence of these agents was negatively correlated wi th body fatness indexes. These results suggest that, in women covering a wide range of adiposity, variations in the lipolytic response of fe moral fat cells to epinephrine may involve changes in the functional b alance between alpha(2)- and p-adrenoceptors and also alterations loca ted at different postreceptor levels.