Changes in charge and ion permeability of PAN-DX dialysis membrane caused by protein adsorption
✍ Scribed by Ken-Ichi Kokubo; Masahiro Taguchi; Kiyotaka Sakai
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 556 KB
- Volume
- 62
- Category
- Article
- ISSN
- 0923-0467
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✦ Synopsis
Some patients on long-term dialysis may suffer from metabolic bone disease owing to abnormal metabolizing of phosphorus and calcium. It is possible to prevent these conditions by controlling serum ion concentrations to an appropriate level, and to do this the rate of ion permeability through the dialysis membrane must be clarified. The rate of ion permeability is influenced by membrane structure and membrane charge. The changes in membrane charge occurring when protein was adsorbed on a polyacrylonitrile dialysis membrane were evaluated for cytochrome (\mathrm{C}), which is positively charged in an aqueous solution at (\mathrm{pH} 7.4) and for (\alpha)-lactalbumin, which is negatively charged at pH 7.4, by means of changes in (\zeta) potential, and these were compared with changes in rates of ion permeability. Changes brought about in membrane structure were also evaluated from changes in the diffusive permeability coefficient of urea, which is a non-electrolyte. After cytochrome C adsorption, the absolute (\zeta) potential of the membrane decreased, and the charge on the membrane became electrically closer to neutral than before the adsorption. In membranes on which (\alpha)-lactalbumin was adsorbed, on the contrary, absolute (\zeta) potential increased and the negative charge on the membrane increased. The diffusive permeability coefficient of urea decreased no matter which protein was adsorbed, but the amount of decrease was slight and there was little change in membrane structure. The diffusive permeability coefficients of sodium hydrogen phosphate and (\mathrm{NaCl}) increased after cytochrome (\mathrm{C}) adsorption and decreased after (\alpha)-lactalbumin adsorption. The changes in electric charge evaluated by (\zeta) potential and changes in the rate of ion permeability due to protein adsorption are in qualitative agreement with ion permeability theory. It is therefore suggested that the (\zeta) potential can be used as an index of membrane charge when evaluating the membrane permeability of ions.