Changes in the metabolism of fatty acids in adipose tissue in obese patients with primary hypertriacylglycerolemia.

Abstract

Changes in the release and esterification of free fatty acids (FFA) in adipose tissue were looked for as a cause of moderate primary hypertriacylglycerolemia (HTG) in five obese subjects. Comparison was made with six obese normolipidemic subjects. The two groups were matched for body weight, tolerance of intravenous glucose, fat cell size, fasting levels of serum immunoreactive insulin, and serum insulin response to an intravenous glucose load. Subcutaneous adipose tissue was incubated in vitro with [1-14C]palmitic acid for 30, 60, and 120 min. There was a significant, twofold increase in the rate of FFA mobilization, but no change of glycerol release in HTG patients. The adipose tissue levels of mono- and diacylglycerols were similar in the two groups of subjects and did not change during incubation. Re-esterification of FFA, calculated from the net changes in medium and in tissue FFA and glycerol release, was lower in HTG patients than in the controls (3 and 12 mumol/10(7) cells/hr, respectively; P less than 0.025). In adipose tissue of HTG patients, the amount of radioactive fatty acids incorporated into triacylglycerols (TG) was 50% lower (P less than 0.025), whereas that incorporated into tissue FFA was three times higher (P less than 0.01) when compared with control patients. It is concluded that, in adipose tissue of obese patients with primary hypertriacylglycerolemia, the esterification of free fatty acids to triacylglycerol is decreased. As a consequence, free fatty acids are mobilized at an increased rate.