Protein catabolism in sham-hemodialysis: the effect of different membranes

To study whether the contact between dialysis membrane of various materials and blood may trigger protein catabolism in muscle and thus contribute to protein depletion in hemodialysis patients we measured the exchange of free amino acids across the leg in healthy subjects undergoing sham-hemodialysis (i.e. in vivo passage of blood through a dialyzer without circulating dialysate). The effect of dialyzers with regenerated cellulose (group CU, n = 16), cellulose acetate (group CA, N = 8) and polysulfone membranes (group PS, n = 8), respectively was studied. Plasma amino acid concentrations were measured in arterial and femoral venous blood and leg blood flow was determined by venous occlusion plethysmography. In group CU the total efflux of all measured amino acids from leg tissues (muscle) increased from 167 +/- 21 nmol/min/100 g tissue in the basal state to 308 +/- 41 nmol/min/100 g tissue at 345 minutes after the start of sham-hemodialysis procedure (p less than 0.01) indicating a protein catabolic effect of contact between blood and regenerated cellulose membranes. In contrast sham-hemodialysis in group CA and group PS, respectively, did not result in significant increases in amino acid efflux from the leg implying that the protein catabolic effect of blood membrane contact depends on the chemical properties of dialysis membranes. In group CU sham-hemodialysis resulted in enhanced net protein breakdown. Increases in arterial concentrations and leg release of 3-methylhistidine suggest that this may be due primarily to increased protein breakdown.