Removal and Metabolism of Triglycerides by Perfused Liver.

The removal of triglycerides from the circulation by the liver has been studied with chylomicrons and emulsions containing labeled fatty acids and glycerol (l-5). During the disappearance of circulating triglycerides, the ratio of labeled glycerol to labeled fatty acids was the same in liver triglycerides as in plasma triglycerides. From these observations, it was concluded that triglycerides are removed intact by the liver. In interpreting these studies, however, it was assumed that glycerol released by hydrolysis of circulating triglycerides is not reincorporated into hepatic triglycerides (6). Since it is difficult to assess the degree to which this may occur, a study of the uptake and metabolism of triglycerides by the perfused rat liver was carried out with another type of labeled compound, glyceryl tripalmitin-l-i%. Tripalmitin can be readily separated from triglycerides containing unsaturated fatty acids (7), and since saturated triglycerides were not formed by the perfused liver, it was possible to differentiate between unmetabolized substrate and newly formed triglycerides in both hepatic cells and blood.