Effect of a single hemodialysis session on endothelial dysfunction

Background: The mechanisms of endothelial dysfunction induced by hemodialysis are unclear. To gain a mechanistic view we have evaluated some of the biochemical markers which directly or indirectly lead to endothelial dysfunction during a single dialysis session. Methods: Time course changes in plasma nitrate levels, arginine (ARG), citrulline, asymmetric dimethylarginine (ADMA), homocysteine (Hcy), malondialdehyde (MDA) and lipoprotein-associated phospholipase A2 (LpPLA2) were evaluated in 27 patients with end-stage renal disease on maintenance hemodialysis. Statistical evaluation of changes was done using analysis of variance for repeated measures and linear regression using generalized estimating equations for repeated measures. Results: Nitrate levels significantly increased as a result of dialysis (p<0.001). Hcy (p<0.05) and ADMA (p<0.001) levels were found to be significantly decreased. ARG/ADMA ratio showed an increase (p<0.001). Presence of oxidative stress (OS) was observed in the form of increased plasma MDA levels. Nitrate levels were negatively associated with Hcy, ADMA and LpPLA2 activity. Conclusion: Our results show an increased production of nitric oxide (NO) during dialysis, which however is affected by increased OS ultimately favoring endothelial dysfunction. Measures to reduce the OS during hemodialysis are needed to get the complete benefit of clearance of circulating inhibitors of NO synthase during dialysis.