Effects of dialysis and transplantation on red cell Na pump function in renal failure

Ion pumping by the erythrocyte Na,K-ATPase has been measured during ouabain-sensitive ⁸⁶Rb flux in 11 non-dialysed patients with chronic renal failure (CRF), 13 patients on haemodialysis (HD), 13 patients on peritoneal dialysis (CAPD) and 15 patients with functional transplants (FT). Flux measurements were performed in plasma and simultaneous estimates of specific ³H-ouabain binding were made. The results indicate that, compared to normal controls, Na,K pump flux was reduced by 21% in CRF (p < 0.01), 30% in HD (p < 0.01), 15% in CAPD (p < 0.02), and was normal in FT. Mean specific ouabain binding sites per cell (± SEM) were: controls 366 ± 16; CRF, 290 ± 16; HD, 344 ± 17; CAPD, 321 ± 18; FT, 345 ± 26. Calculation of mean turnover rate per pump site indicated that patients on HD showed a 30% reduction compared to controls (influx 55 K ions/s versus 79 K ions/s, p < 0.01). Cross-incubation experiments suggest that the lowered pump flux seen in the CRF and HD groups was due to plasma factors. This work shows that erythrocyte Na,K pump number is reduced in CRF, while patients on maintenance HD have normal pump numbers per erythrocyte but reduced pump turnover.