Dialysis improves endothelial function in humans

Background. Circulating inhibitors of endothelial function have been implicated in the pathogenesis of vascular disease in chronic renal failure. The aim of this study was to determine if lowering the plasma concentration of these and other dialysable toxins improves endothelial function. To do this we compared the acute effects on endothelial function of single episodes of haemodialysis with automated peritoneal dialysis. We hypothesized that endothelial function would improve after dialysis, with a greater effect seen after haemodialysis due to more substantial clearance of endothelial toxins per-treatment. Methods. Subjects with end-stage renal failure undergoing haemodialysis (n = 16) or automated peritoneal dialysis (n = 14) were investigated. Endothelial function was determined using vascular ultrasound to measure flow-mediated dilatation of the brachial artery and was compared with the dilatation caused by sublingual glyceryl trinitrate. Endothelial function was assessed before and after a single dialysis treatment. Plasma concentrations of the inhibitors of endothelial function, asymmetric dimethyl-L-arginine and homocysteine were measured. Flow-mediated dilatation was expressed as percentage change from basal diameter and analysed using Student's t test. Results. The plasma concentration of circulating inhibitors of endothelial function was reduced after haemodialysis but not peritoneal dialysis. Haemodialysis increased flow-mediated dilatation from 4.0 +/-1.0% to 5.8 +/-1.2% (P <0.002). These changes persisted for 5 h but returned to baseline by 24 h. Automated peritoneal dialysis had no acute effect on flow-mediated dilatation (5.9 +/-1.1% vs 5.4 +/-0.8% after, P >0.5). There were no effects of either dialysis modality on dilatation to glyceryl trinitrate. Conclusions. Short-term reduction of circulating inhibitors of endothelial function by haemodialysis is associated with increased flow-mediated dilatation. These data suggest that dialysable endothelial toxins have deleterious effects on endothelial function that are rapidly reversible.