The effects of nicotinic acid treatment on high density lipoprotein particle size subclass levels in hyperlipidaemic subjects.

Twenty-three consecutive hyperlipidaemic patients were treated with 4 g nicotinic acid daily for 6 weeks. The treatment resulted in the expected reduction of serum very low density (VLDL) and low density lipoproteins (LDL) and in the increase of high density lipoproteins (HDL). The cholesterol concentration of the latter fraction rose by 45%. The HDL fraction was isolated by ultracentrifugation and then subjected to gradient gel electrophoresis (gge), in order to determine the HDL particle size distribution, before and after treatment. The increase of HDL was almost exclusively confined to the largest HDL (gge) subclass HDL-2b, the protein content of which rose by 183%. In contrast, there was about a 25% decrease in the concentration of the smallest HDL(gge) subclasses, HDL-3b and HDL-3c. The levels of HDL-2b and VLDL triglycerides showed a significant inverse correlation before, as well as after, treatment. Multiple partial correlation analysis demonstrated, however, that the nicotinic acid induced increase in HDL-2b concentration showed a highly significant inverse correlation to the decrease in LDL cholesterol, but not to the decrease in VLDL triglyceride levels. Recent studies, in particular those regarding the negative correlation between both the degree and progression of coronary atherosclerosis and the HDL-2b concentration in young male myocardial infarct patients, suggest that the profound increase of HDL-2b levels by nicotinic acid treatment in hyperlipidaemic patients might be of considerable importance in the protection of coronary atherosclerosis.