Effect of different fatty acids on triacylglycerol secretion in isolated rat hepatocytes

Lipoprotein triacylglycerol secretion was studied in isolated rat hepatocytes incubated with different albumin-bound fatty acids and labeled glycerol. The release of labeled triacylglycerol was stimulated more by unsaturated fatty acids than by saturated ones. When lipoprotein secretion was related to cell triacylglycerol synthesis, an effect of unsaturation was no longer observed. Instead the secretion rate, expressed in this manner, increased with increasing fatty acid chain length. For the first time, the secretion of molecular species of triacylglycerol has been studied. The distribution of labeled glycerol among different species was the same in the cells and in th secreted product, indicating that different triacylglycerols were secreted without selectivity. It is concluded that the fatty acid structure influences lipoprotein triacylglycerol secretion and it is emphasized that the effects observed depend on the method of quantitation of the secretion rate.