Abstract
Recently, a new method for measuring serum lipid peroxide (LPO) has been developed. Reaction between lipid hydroperoxide and a derivative of methylene blue (MCDP; 10-N-Methylcarbamoyl-3, 7-dimethylamino-10 H-phenothiazine) produces methylene blue, by which serum lipid peroxide can be calculated. By using this new method, (1) we tried to determine the values of serum LPO in healthy subjects and in patients with various diseases, and (2) we also investigated the distributions of LPO in serum lipoprotein fractions, separated by high performance liquid chromatography (HPLC). Results were as follows;
(1) In healthy subjects, LPO level was 7.63±2.78nmol/ml. The level in patients suffering from cerebrovascular accidents (mainly in acute phase) was lower than in healthy subjects, while the levels in patients with hypertension and hyperlipidemia were higher. (2) By HPLC, only one peak of LPO was detected. This peak was possibly located in HDL-fraction, and there were no detectable peaks in LDL-fraction.
There have been several reports on the detection of LPO in lipoprotein fractions, which said, in contrast to our results, that high levels of LPO were found in two fractions, i.e. both LDL- and HDL-fractions. This difference might be due to the differences in analytical methods. Those reports used ultracentrifugation technique for lipoprotein separation, and TBA method for LPO detection. There exists a possibility that ultracentrifugation technique denatures lipoproteins. In our experiment, it is unlikely that the peak was located in LDL-peak, judged from the elution pattern. However, whether this peak was located in HDL-peak is now under investigation. Our new analytical technique is the combination of HPLC and the new method of LPO detection, and, in this system, we observed only one peak of LPO. Further investigation is needed to clarify the quality and the quantity of distribution pattern of serum LPO.
