Age-related increases in plasma phosphatidylcholine hydroperoxide concentrations in control subjects and patients with hyperlipidemia

Background The basal lipid peroxide concentration in the plasma of patients with hyperlipidemia may be related to atherosclerosis. Quantitative determ ination of lipid peroxides in the plasma is an important step in the overal l evaluation of the biochemical processes leading to oxidative injury. Unfo rtunately, the currently available methods for lipid peroxidation lack spec ificity and sensitivity. Methods: Hyperlipidemic patients (44 males and 50 females), ages 12-82 year s (mean +/- SE, 53 +/- 2.3 years for males, 58 +/- 2.0 years for females, a nd 56 +/- 14 years for total cases), and normolipidemic volunteers (control s, 32 males and 15 females), ages 13-90 years (49 +/- 4 years for males, 65 +/- 4 years for females, and 55 +/- 24 years for total cases), were recrui ted in the present study. Plasma phosphatidylcholine hydroperoxide (PCOOH) was determined by chemiluminescence-HPLC (CL-HPLC). Results: Plasma PCOOH concentrations increased with age in both controls an d hyperlipidemic patients. However, the mean plasma PCOOH concentration in patients with hyperlipidemia (331 +/- 19 nmol/L; n = 94) was significantly (P <0.001) higher than in the controls (160 +/- 65 nmol/L; n = 47). Plasma PCOOH concentrations were similar in three hyperlipidemic phenotypes: hyper cholesterolemia (IIa), hypertriglyceridemia (IV), and combined hyperlipidem ia (IIb). The mean plasma PCOOH in patients with treatment-induced normaliz ed plasma lipids was 202 +/- 17 nmol/L. There was no significant correlatio n between plasma PCOOH concentration and total cholesterol, triglycerides, or phospholipids in hyperlipidemic patients. For all subjects, there was a significantly positive correlation between plasma PCOOH and each lipid (tot al cholesterol, P = 0.0002; triglycerides, P = 0.0137; and phospholipids, P <0.0001). Analysis of fatty acids composition of plasma phosphatidylcholin e showed significantly low concentrations of n-6 fatty acids moieties (lino leic acid and arachidonic acid) in patients compared with controls. Conclusions: Our results suggest that an increase in plasma PCOOH in patien ts with hyperlipidemia may be related to the development and progression of atherosclerosis, particularly in the elderly. Measurement of plasma PCOOH is useful for in vivo evaluation of oxidative stress. (C) 2000 American Ass ociation for clinical Chemistry.