HEMODIALYZER BIOCOMPATIBILITY AND ERYTHROCYTE STRUCTURE AND FUNCTION

There is controversy as to the clinical importance of providing haemod ialysis (HD) with biocompatible versus non-biocompatible membranes. Th e effects of both acute and chronic dialysis with a biocompatible memb rane (polyacrylonitrile, PAN) and a non-biocompatible membrane (cuprop hane, CU) on the structural and functional properties of human erythro cytes have been examined. All 27 studied RD patients had increased ery throcyte osmotic fragility (OF) compared to controls; a single CU HD d ecreased mean OF (% lysis) by 13% without altering cell cholesterol. A single PAN HD decreased OF by a significantly greater amount (24%) an d was associated with a 20% reduction in cell cholesterol. Chronic PAN HD for 6 months was associated with a sustained reduction in osmotic fragility compared to chronic CU HD (mean lysis 16% vs 45%) with no di fferences in mean pre-HD cell cholesterol. A single CU HD was associat ed with increased mean erythrocyte malonyldialdehyde (MDA) and reduced membrane content of spectrin and band 3 and this was significantly di fferent from the effects of PAN. A single CU or PAN HD had no signific ant action on reduced glutathione (GSH), ankyrin, actin or sodium pump activity. Chronic HD was associated with increased GSH, and decreased ankyrin and band 3 protein compared with controls but the results for CU and PAN were not different. There was a non-significant tendency f or higher MDA levels after chronic CU HD compared to PAN. These result s indicate that the structural integrity of erythrocytes is improved b y PAN HD with respect to CU but this difference cannot easily be ascri bed to gross changes in structural proteins, ionic homeostasis or oxid ation status. (C) 1997 Elsevier Science B.V.