IN VITRO STUDIES OF METABOLISM OF FAT CELLS ISOLATED FROM BLACK AND WHITE OBESE SUBJECTS E.P. BUTHELEZI IN VITRO STUDIES OF METABOLISM OF FAT CELLS ISOLATED FROM BLACK AND WHITE OBESE SUBJECTS

The study aimed to quantify differences in lipid metabolism and insulin sensitivity in black and white subjects to explain ethnic clinicopatho logical differences in type 2 diabetes. The in vitro inhibitory effect of insulin on lipolytic activity and of its stimulating effect on glucose uptake by adipocytes isolated from obese black and white women were investigated. Fasting plasma levels o f insulin and free fatty acid (FFA) in black and white women were 67±lpmol/l vs. 152±4pmol/l (p<0.01); 890±131|imol/l vs. 425+4 jimol/L (pO.Gl) respectively. Isolated femoral adipocytes from white women were more responsive to insulin than those from black women with 0.72mno]/l causing a 55+4 % inhibition of isoprotorenol-stimulated lipolysis compared to a 27+10 % inhibition in black women (p<0.01). Furthermore, isolated femoral adipocytes from white women showed improved glucose uptake (247+36%) than those from black women (128+28%) in the presence o f 7.0nmol/l insulin (p<0.05). The low responsiveness of adipocyte lipolytic activity to insulin in black women in the presence o f relatively low insulin levels, may account for the high plasma FFA levels observed in these women which may, in turn account for their higher in vivo insulin resistance. It is proposed that the pathogenesis of glucose intolerance within the black obese population is strongly influenced by their adipocyte metabolism. 1, Ernest Philani Buthelezi, declare that this dissertation is my own work and has not been submitted or incorporated in another dissertation or thesis for any other degree