Correlations between the apoprotein C composition of very-low-density lipoproteins and triglyceridemia in subjects with type IV hyperlipoproteinemia.

The protein composition of apoprotein C regarding peptides CII, CIII1, and CIII2 has been studied in VLDLs in 59 normal or hypertriglyceridemic subjects. The percentages of the peptides found in each subject were correlated with serum triacylglycerol levels. There are very good correlations between the proportion of VLDL apo CII and triglyceridemia (r = -0.63) and between the proportion of CII1 and triglyceridemia (r = 0.66). The proportion of apo CII decreases as triacylglycerol level increases, whereas the proportion of apo CII1 increases under the same conditions. The percentage of apo CII2 varies in the same way as does apo CII, but to a lesser degree. The apo CII/CIII1 and apo CIII2/CIII1 ratios decrease as triglyceridemia increases. In contrast, the apo CII/CIII2 radio, though reduced, is not significantly modified. Mechanisms are reviewed that could lead to changes in apoprotein C in subjects with hyperlipoproteinemia, and the possible relationship with lipoprotein lipase activity is discussed.