Hemodialysis impairs endothelial function via oxidative stress - Effects of vitamin E-coated dialyzer

Background-Patients who undergo hemodialysis experience accelerated atheros clerosis and premature death. Recent evidence suggests that endothelial dys function proceeds to and exacerbates atherosclerosis. It remains unknown wh ether hemodialysis per se causes endothelial dysfunction. Methods and Results-We evaluated endothelial function estimated by flow-med iated vasodilation during reactive hyperemia using high-resolution ultrasou nd Doppler echocardiography before and after a single session in patients o n maintenance hemodialysis. Several studies have shown that the imbalance b etween pro-oxidant and antioxidant activities in hemodialyzed patients resu lts in high oxidative stress, which causes lipid peroxidation and endotheli al injury. Accordingly, we investigated the effects of antioxidative modifi cation during hemodialysis on endothelial function using a vitamin E- coate d cellulose membrane dialyzer. Nonspecific endothelium-independent vasodila tion was measured after administration of a sublingual glyceryl trinitrate spray (0.3 mg). A single session of hemodialysis by noncoated dialyzer impa ired flow-mediated vasodilation (P<0.05) associated with increased plasma l evels of oxidized LDL (P<0.05), an index of oxidative stress. Hemodialysis by vitamin E-coated membrane prevented dialysis-induced endothelial dysfunc tion and increases in oxidized LDL. Plasma levels of oxidized LDL were inve rsely correlated with the magnitudes of flow-mediated vasodilation (r = -0. 53, P < 0.001). Hemodialysis by noncoated or vitamin E-coated membrane did not affect glyceryl trinitrate-induced endothelium-independent vasodilation . Conclusions-Our findings indicate that hemodialysis per se impairs endothel ial function, possibly by increasing oxidative stress.