[Oxidative stress and endothelial dysfunction at different serum uric acid levels].

Objective: To investigate the state of oxidative stress in the subjects with different levels of serum uric acid and to explore the cause of endothelial dysfunction induced by hyperuricemia.

Methods: Male subjects with normal serum uric acid or hyperuricemia were enrolled in this study. According to the levels of serum uric acid, all the participants were divided into five groups. Every group consisted of about fifty subjects. Plasma malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were determined. In the mean time plasma nitric oxide (NO), plasminogen activator inhibitor-1 (PAI-1), endothelin-1 (ET-1) and other biochemical variables were also determined.

Results: When the serum uric acid level was more than 380 micromol/L, the levels of plasma MDA, SOD, GSH-Px, PAI-1 and ET-1 became higher, while the level NO became lower (P < 0.05). However SOD and GSH-Px became much lower when the serum uric acid level was more than 420 micromol/L. Multivariate stepwise regressive analysis showed that PAI-1 was positively related to MDA, UA, HOMA-IR and TG, but negatively related to SOD and NO (t = -3.64 - 6.08, P < 0.05). ET-1 was positively related to MDA, UA, HOMA-IR and negatively related to NO, GSH-Px and SOD (t = -4.75 - 6.35, P < 0.05).

Conclusions: It is indicated that oxidative stress became much obvious when the serum uric acid level was more than 380 micromol/L. Oxidative stress, high serum uric acid level and insulin resistance may result in endothelial dysfunction.