EFFECTS OF NICOTINIC-ACID TREATMENT ON FATTY-ACID COMPOSITION OF PLASMA-LIPIDS AND ADIPOSE-TISSUE IN HYPERLIPEMIA

Effects of 6-week treatment with 4 g daily of nicotinic acid on fatty acid composition in different serum lipids and in adipose tissue glycerides were studied in 31 hyperlipidemic patients. The percentages of eight fatty acids in triglycerides, phospholipids and cholesteryl esters of whole plasma as well as in subcutaneous adipose tissue glycerides were measured. Nicotinic acid treatment produced decreases in triglyceride and total cholesterol concentrations of VLDL and LDL, whereas HDL total cholesterol levels in serum increased after drug therapy, all p<0.01. There were reductions in the relative contents of myristic acid in plasma phospholipids (from 0.4% to 0.3%; p<0.05) and cholesteryl esters (from 0.9% to 0.7%; p<0.001). There were decreases in the percentages of stearic acid in plasma phospholipids (from 17.0% to 15.0%) and cholesteryl esters (from 1.2% to 1.0%; both p<0.001). The relative contents of polyunsaturated fatty acids, mainly linoleic acid, in plasma phospholipids were increased (from 32% to 33.5%; p<0.05). There were reductions in the linolenic acid contents of adipose tissue (from 1.5% to 1.1%) and plasma triglycerides (from 1.1% to 0.8%), both p<0.05, possibly indicating increased conversion of linolenic acid to prostaglandins. There was no relationship between changes in the percentages of individual fatty acids and changes in triglyceride or total cholesterol levels of whole serum and its VLDL, LDL and HDL fractions. Our results suggest that although there are some numerically small changes in the fatty acid compositions of circulating lipoproteins induced by nicotinic acid treatment, these changes do not explain the strong effects of this drug on triglyceride and total cholesterol levels of serum lipoproteins.