What happens after lipoprotein lipase? A low fatty acid incorporation into adipose tissue (FIAT) in hypertriglyceridaemia-experimental and clinical studies.

The Fatty acid Incorporation into human Adipose Tissue (FIAT), the metabolic step after the hydrolysis of plasma triglyceride (TG)-bound fatty acids (FA) by lipoprotein lipase, was studied by an in-vitro technique to investigate its role and reactions to various substrates, drug and dietary treatments in hypertriglyceridaemia (HTG). We found that FIAT was reduced, P less than 0.001, in patients with HTG and a recent myocardial infarction compared to normotriglyceridaemic (NTG) patients. Patients with very high plasma TG levels had the lowest FIAT. There were highly significant positive correlations between FIAT in several subcutaneous regions and omental fat with highest activities in the omental fat. FIAT increased approximately linearly with increasing medium FA concentrations in both NTG and HTG patients. Low values were more common in HTG. In both groups, however, the rate of fatty acid mobilizing lipolysis was significantly decreased when FA increased. FA thus seems to have important effects on both FIAT and rate of lipolysis. FIAT was increased when rate of fatty acid mobilization was inhibited in vitro by the beta-blocker oxprenolol. FIAT decreased, P less than 0.05 and lipolysis increased, P less than 0.01 after one week of treatment with an adenosine derivate BM 11.189. Serum TG were not affected in that study but decreased, P less than 0.001, when HTG patients were treated by diet and clofibrate for two weeks presumably because this treatment increased FA-removal, ie FIAT. The results suggest that variations in the FIAT activity seems to play an important role in determining plasma TG levels.