Dialysis improves endothelial function in humans

Background. Circulating inhibitors of endothelial function have been implic ated 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 o f haemodialysis with automated peritoneal dialysis. We hypothesized that en dothelial function would improve after dialysis, with a greater effect seen after haemodialysis due to more substantial clearance of endothelial toxin s per-treatment. Methods. Subjects with end-stage renal failure undergoing haemodialysis (n = 16) or automated peritoneal dialysis (n = 14) were investigated. Endothel ial function was determined using vascular ultrasound to measure flow-media ted 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 hom ocysteine were measured. Flow-mediated dilatation was expressed as percenta ge 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. Haemo dialysis 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 dila tation (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 dilata tion. These data suggest that dialysable endothelial toxins have deleteriou s effects on endothelial function that are rapidly reversible.