Erythrocyte Sodium Transport in Dialyzed Uremic Patients

摘要

To investigate the status of the Na⁺ concentration and ionic fluxes in red cells of human subjects with dialyzed chronic uremia, the authors measured the Na⁺-K⁺ pump activity as well as Na⁺-K⁺ cotransport (CoT), Na⁺-Li⁺ countertransport (CTT) and Na⁺ passive permeability in erythrocytes from 37 normal subjects and 23 chronic uremic patiens receiving maintenance hemodialysis. The mean intracellular Na⁺ concentration [Na⁺]i value in the pre-dialytic group was significantly lower than that in control subjects (p<.0001), but tended to recover to the normal value of [Na⁺]i in the post-dialytic group. The mean intracellular K⁺ concentration value in the post-dialytic group was significantly higher than that of the control group (p<.001), but not significantly different from that of the pre-dialytic group. It was found that the Na⁺-K⁺ pump activity of erythrocytes in the pre- and post-dialytic groups markedly decreased over that of the normal control group with statistical significance (p<.0001, respectively). The Na⁺-K⁺ pump activity in the post-dialytic group, however, tended to recover, but not significantly. The rate constant for ouabain-sensitive Na⁺ efflux in the post-dialytic group was significantly decreased over that of the normal controls (p<.05). The authors observed a significant decrease of the Na⁺ CoT value (p<.001 respectively) and rate constant for Na⁺ CoT (p<.05, respectively) in the patients with pre- and post-dialytic uremia vs. that of normal subjects. Also, the authors observed a marked decrease of the Na⁺-Li⁺ CTT value in the patients in the pre- and post-dialytic groups than that of the control subjects (p<.05, respectively). Passive Na⁺ permeability in the patients with pre-dialytic uremia was decreased markedly compared to the normal subjects (p<10⁻⁵), but its value in the post-dialytic group tended to recover to the normal value. In conclusion, our studies demonstrate that another possible mechanism of inhibition of the Na⁺-K⁺ pump in pre- dialytic uremia might then be a secondary adaptive response of the cell to maintain normal intracellular ion concentration and transmembrane ion gradients in the face of the reduced [Na⁺]i due to decreased passive Na⁺ permeability.