Erythrocyte Na+ and K+ transport systems in children with Bartter syndrome: increase in passive sodium permeability.

Na+ and K+ intracellular content was studied in five children with Bartter syndrome and their age and race-paired controls. Na+ and K+ pump (ouabain sensitive) fluxes, Na+-K+ co-transport (furosemide sensitive), and rate constants of passive Na+ and K+ permeability were determined in each patient and control and also in six parents. The results show that in Bartter syndrome, there is a significant increase in the rate constant of passive Na+ permeability without any change in passive K+ permeability. This increase in the rate constant of passive permeability might explain at least partially the increased intracellular Na+ concentration also found in these patients. Moreover, the maximal rate of ouabain sensitive Na+ efflux was increased slightly, and co-transport fluxes were variable. Parents of patients had normal erythrocyte fluxes.