INVIVO TRIGLYCERIDE SECRETION AND HEPATIC AND PLASMA-LIPIDS IN RATS FED MEDIUM-CHAIN TRIGLYCERIDES, TRIPELARGONIN, OR CORN-OIL

The relationship between in vivo triglyceride secretion and the concentrations of cholesterol and triglycerides in liver and plasma was studied in fasted, male Sprague Dawley rats (150-170 g) fed 16% fat diets containing 8-16% medium chain triglycerides (68% C 8:0 and 24% C 10:0), 14% tripelargonate (C 9:0), or corn oil. Plasma and liver cholesterol concentrations were 10-20% lower (P < 0.05), and hepatic activity of 3-hydroxymethyl-3-glutaryl Coenzyme A reductase was 44-66% lower (P < 0.05) with ingestion of 14% medium chain triglycerides or tripelargonin than corn oil. Liver triglyceride concentrations were 19-44% lower (P < 0.01) with ingestion of 14% medium chain triglycerides or tripelargonin than corn oil. Using the Triton WR-1339 technique, the rate of triglyceride secretion (mg/min X 100 g body wt), plasma triglyceride pool size, and the fractional rate constant for triglyceride secretion were not significantly different among treatment groups. This suggests that a greater rate of triglyceride secretion is not the primary factor associated with lower hepatic triglyceride levels in rats fed medium chain triglycerides. In summary, 10-20% lower plasma and liver cholesterol concentrations were noted with ingestion of saturated, medium-chain-length fatty acid triglycerides containing 8, 9, or 10 carbons compared to corn oil.