Essential fatty acid deficiency and plasma triglyceride turnover in rats

Hepatic triglyceride secretion in essential fatty acid-deficient rats was examined by three separate techniques in an effort to resolve conflicting evidence on the question of whether essential fatty acid deficiency altered hepatic triglyceride secretion in vivo. First, plasma triglyceride turnover was measured by intravenous injection of [2-3H]glycerol trioleate. Equations of the kinetics were formulated based on a single, open pool model. Turnover rates and pool sizes of plasma triglyceride were calculated from these equations. Second, [2-3H]glycerol was injected, and apparent rate constants for plasma triglyceride secretion and clearance were calculated by kinetic analysis. Third, Triton WR-1339 was used to inhibit lipoprotein clearance from blood plasma, and rates of plasma triglyceride accumulation were measured. The results of these studies showed that the rate of hepatic triglyceride secretion was 2-3 times greater in essential fatty acid-deficient rats than in nondeficient controls. The increase in triglyceride secretion, as well as the higher level of liver triglyceride typical of essential fatty acid-deficient rats, could be caused by increased lipogenesis and increased mobilization of fatty acids from adipose tissues.