Hypercholesterolemia and triglyceride secretion rates in monkeys fed different dietary fats

The influence of hypercholesterolemia on the triglyceride secretion rate was studied in both squirrel and cebus monkeys fed coconut oil, corn oil, or safflower oil. The triglyceride secretion rate (TGSR) was determined in vivo following the administration of Triton WR1339, which blocks the clearance of very low density lipoprotein (VLDL). Thus, the increase observed in circulating triglyceride after Triton administration presumably reflecte hepatic triglyceride (VLDL) secretion in the fasted state. The VLDL-TGSR was lowest in hypercholesterolemic monkeys and highest in those fed unsaturated fat diets and having a low serum cholesterol. In all instances, TGSR was inversely correlated with the plasma cholesterol concentration. While a definitive explanation for these observations must await further investigation, the possibility that circulating low density lipoprotein (LDL) acts to feed back on VLDL secretion is discussed. The decreased TGSR associated with the diet-induced cholesterolemia also implies clearance of VLDL is impaired under these conditions.