EFFECTS OF DIETARY FATTY-ACIDS ON THE ACTIVITY OF GLUCOSE-TRANSPORT IN ADIPOCYTES

Lipid structure of plasma membrane plays an important role in regulating D-glucose transport in adipocytes. To investigate the effects of diet-induced alteration in cellular fatty acids on the activity of D-glucose transport in adipocytes, we fed rats iso-nutrient diets with high (20 energy% safflower oil) or low (2 energy% safflower oil plus 18 energy% beef tallow) safflower oil. After 31 days, adipocytes were isolated from epididymal fat pads using collagenase and incubated at 310-degrees-K (37-degrees-C) in KRB buffer containing 3% bovine serum albumin. Two-deoxyglucose transport into adipocytes was measured using an oil centrifugation method at 2, 5, and 10 minutes of incubation. The composition of fatty acids was analyzed in the fat pad and adipocyte incubation mixture by using gas chromatography. In the fat pad, fatty acids were composed of 61% linoleic, 18% each of palmitic and oleic, and 0.7% arachidonic acids in the high safflower oil group, and 56% oleic, 31% palmitic, 8% linoleic acids in the low safflower oil group. The compositions of dietary fatty acids were reflected directly in the composition of fatty acids in the fat pads and in the compositions of fatty acids released from isolated adipocytes. The high safflower oil diet significantly increased D-glucose transport in adipocytes compared with the low safflower oil diet group (8.66 vs 6.31 nmol 2-deoxyglucose transport per 10(6) cells at 5-minute incubation). The results suggest that lipid composition in the tissue may have a regulatory effect on adipocyte glucose transport. Diet-induced high polyunsaturated fatty acids in the tissue facilitates carrier-mediated D-glucose transport in adipocytes.