[The significance of the distribution of apolipoprotein C-III in serum lipoproteins].

Apolipoprotein C-III(CIII) is distributed mainly into VLDL and HDL, and into LDL and chylomicron to a lesser degree. CIII has been proposed to inhibit lipolysis of triglyceride(TG), but the significance of its distribution in several lipoproteins is not well understood. In this study using immunofixation electrophoresis, that issue was re-evaluated. The method was advantageous in excluding CIII in chylomicron. Concentration of CIII in pre-beta and beta lipoproteins(beta-CIII) was positively correlated with serum TG, and the ratio of CIII in alpha lipoprotein(alpha-CIII) to beta-CIII(alpha/beta CIII) was negatively correlated with TG, and the ratio was positively correlated with cholesterol of alpha lipoprotein(alpha-Chol) and negatively with pre-beta-Chol, so that the ratio can be considered a predictor of the metabolic rate of apoB-containing lipoproteins(LpB). There was a tendency for negative correlation between beta-CIII and alpha-CIII. alpha/beta CIII was positively correlated with HDL-ch/apoA, which had previously been defined as an inverse predictor of catabolic rate of apoA-I. These findings indicate that distribution of CIII into serum lipoproteins being dependent upon lipolysis may induce a linkage of catabolic rate of apoA-I in inverse proportion to metabolic rate of LpB.