title: Dialysis filter type determines the acute effect of haemodialysis on endothelial function and oxidative stress.
abstract: BACKGROUND
  Endothelial function of large arteries is impaired in chronic haemodialysis patients and oxidative stress due to the dialysis procedure has been suggested as a causal factor. However, it is not clear whether different types of dialysis membranes affect endothelial function differently. Therefore we determined endothelium-dependent, flow-mediated dilatation (FMD) of the brachial artery as well as markers of oxidative stress immediately before and after haemodialysis (HD) with either a cellulosic cuprophane or a synthetic polysulphone dialyser in a blinded, randomized, cross-over study.
  
  
  METHODS
  Twelve haemodialysis patients (age 55+/-3 years, time on dialysis 20+/-2 months, mean fluid change -1782+/-21 ml, systolic/diastolic blood pressure 139/75 mmHg) were included. Using a multi-gate-pulsed Doppler system (echo-tracking device) brachial artery FMD and nitroglycerine-induced, endothelium-independent vasodilatation (NMD) were measured. Patients were randomized to HD with either a polysulphone or a cuprophane membrane and were crossed over to the other filter. Investigators were blinded to the type of membrane used. Serum concentrations of oxidized LDL (oxLDL) and alpha-tocopherol as markers of oxidative stress were measured before and after each dialysis session.
  
  
  RESULTS
  Data are given as mean+/-SEM. Treatment with polysulphone filter HD did not significantly affect FMD (baseline 9.3+/-2.0% vs after HD 9.6+/-1.8%). After dialysis with a cuprophane membrane FMD decreased from 9.4+/-2.1 to 7.4+/-1.8% (P<0.05). NMD was not significantly affected by HD irrespective of the membrane material used. Serum levels of oxLDL were not changed by either treatment; however, alpha-tocopherol concentrations fell significantly after dialysis with the cuprophane filter (baseline 18.0+/-2.3 after HD 16.6+/-1.3 micro g/ml, P<0.05), while alpha-tocopherol levels remained unchanged when the polysulphone membrane was used.
  
  
  CONCLUSIONS
  The type of dialysis filter membrane determines the acute effect of haemodialysis on arterial endothelial function. Differences in biocompatibility and oxidative stress may account for the observed differential effects, since the decrease of FMD after dialysis with a cellulosic cuprophane membrane-but not with a synthetic polysulphone membrane-was associated with a reduction in serum vitamin E.
authors.affiliation: Department of Internal Medicine D (Nephrology), University of Münster, Germany. koschm@uni-muenster.de
authors.forename: Markus
authors.initials: M
authors.lastname: Kosch
authors.forename: Andrea
authors.initials: A
authors.lastname: Levers
authors.forename: Manfred
authors.initials: M
authors.lastname: Fobker
authors.forename: Michael
authors.initials: M
authors.lastname: Barenbrock
authors.forename: Roland M
authors.initials: RM
authors.lastname: Schaefer
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Rahn
authors.forename: Martin
authors.initials: M
authors.lastname: Hausberg
mesh_terms: D000208:Acute Disease; D000328:Adult; D001672:Biocompatible Materials / Q000627:therapeutic use*; D001916:Brachial Artery / Q000503:physiopathology; D002318:Cardiovascular Diseases / Q000209:etiology* / Q000503:physiopathology* / Q000517:prevention & control; D002482:Cellulose / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D008297:Male; D008567:Membranes, Artificial; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D011108:Polymers / Q000627:therapeutic use*; D006435:Renal Dialysis / Q000009:adverse effects*; D013450:Sulfones / Q000627:therapeutic use*
chemical_list: D001672:Biocompatible Materials; D008567:Membranes, Artificial; D011108:Polymers; D013450:Sulfones; C017662:polysulfone P 1700; D002482:Cellulose; C009865:cuprammonium cellulose