[Effects of aging on oxidisability of low density lipoprotein]

Oxidised LDL is taken up by macrophages via scavenger receptors, leading to foam cell formation and is thus considered to contribute to atherogenesis. Aging results in the increase of lipids and the decrease of antioxidant enzyme activity in serum. In this study, we investigated the effects of aging on LDL oxidisability. We measured LDL oxidation lag time, plasma lipids, albumin and uric acid were examined in 306 Japanese (169 men, 137 women). The mean +/- SE of LDL oxidation-lag time in subjects was 58.9 +/- 1.0 min. The lag time (80.3 +/- 4.8 min) was longest in subjects in their 20 s and shortest in those in their 40 s (58.9 +/- 1.0 min). The longest lag time was in second-decade men (88.9 +/- 6.2 min) and shortest in fourth-decade women (50.7 +/- 2.2 min), and these results were similar even excluding subjects with abnormal biochemical data (total cholesterol, triglyceride, GOT, GPT, gamma GTP, creatinine and glucose). We analyzed the effects of various factors on lag time using multiple linear regression. Aging, uric acid and LDL-cholesterol significantly influenced lag time. Our results suggest that LDL oxidisability might been regulated by aging, changes in LDL-cholesterol with aging and variations in physical antioxidant function.