Lipid peroxide levels in type II hyperlipoproteinemic subjects.

The purpose of this study was to evaluate, under the most rigorous precautionary measures against in vitro oxidation, whether the baseline lipid peroxide levels in hypercholesterolemic subjects were higher than those in normolipidemic subjects. Two methods were employed: thiobarbituric acid (TBA), and hemoglobin-methylene blue (HbMB). Blood was collected into EDTA tube and centrifuged at 4 degrees C for 30 min to collect plasma, then protected from in vitro oxidation with preservatives and N2. Serum was from blood samples allowed to clot at 20 degrees C for 1 h, then protected from oxidation. Determination of lipid peroxide was carried out within 2 h of blood collection. Results from 35 hypercholesterolemic and 34 control subjects showed that lipid peroxide levels obtained from both methods were significantly higher in serum than in plasma for both groups, suggesting a greater rate of lipid peroxidation occurred in serum during clot formation. However, no significant difference in lipid peroxide levels was found between patients and controls in either serum or plasma by either assay method. No correlation existed between lipid peroxide values and plasma cholesterol or LDL-cholesterol levels. These results suggest that the mechanism for a higher tendency towards atherosclerosis in hypercholesterolemic subjects is not related to baseline levels of plasma lipid peroxide.