Transmembranous Transport and Adsorption of Beta-2-microglobulin during Hemodialysis using Polysulfone, polyacrylonitrile, polymethylmethacrylate and Cuprammonium Rayon Membranes

Abstract

Beta-2-microglobulin (b2M) was identified as a causative agent of amyloidosis associated with long-term hemodialysis (HD). Therefore, we examined handling of b2M during a 4-hour hemodialysis session. We compared b2M adsoprtion and diffusive/convective elimination between high-flux membranes such as polysulfone (PS; F 60®, Fresenius), polyacrylonitrile (AN 69; Filtral R , Hospal) and polyacrylonitrile (PAN, PAN 12CX2 R , Asahi) and less permeable membranes such as cuprammonium rayon (CR; AM 160 H R , Asahi) and polymethylmethacrylate (PMMA; BK-1.6 U R , Toray). To calculate total elimination, arterio-venous differences of b2M were measured at 0, 5, 20, 60 and 240 minutes; dialysate concentration was analyzed to evaluate diffusive/convective transport. Differences between recovery in dialysate and total removal were regarded as amount removed by adsorption. Total elimination per 4-hour hemodialysis session and per m 2 membrane surface was 154.7 ± 12.3 mg for the PS, 137.8 ± 28.4 mg for the AN 69, 179.8 ± 47.5 mg for the PAN, 130.8 ± 11.8 mg for the PMMA and 14.4 ± 16.0 mg for the CR membrane. Diffusive/convective transport was 128.0 ± 18.1 mg for PS, 54.7 ± 8.1 mg for AN 69 and 106.5 ± 20.8 mg for PAN and insignificant for PMMA and CR. Adsorption was 26.7 ± 4.3 mg for PS, 83.1 ± 29.0 mg for AN 69 and 59.8 ± 17.2 mg for PAN. Besides transmembranous transport sorption is an important mode of elimination. Weekly endogenous generation rate is about twice as high as b2M elimination