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

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. Etude de divers systemes de transport du Na+ et du K + a travers la membrane erythrocytaire chez des enfants souffrant du syndrome de Bartter: Augmentation specifique de la permeabilite passive du sodium. La concentration intra-erythrocytaire en Na+ et K+ a ete mesuree chez cinq enfants souffrant du syndrome de Bartter couples a des temoins du meme âge et de la meme race. Les flux de la pompe a sodium (sensibles a la ouabaine), le co-transport du Na+ et du K+ (sensible a la furosemide) et le taux de permeabilite passive du Na+ et du K+ ont ete determines chez chaque patient et leur temoin ainsi que chez six parents de patients. Nos resultats demontrent que dans le syndrome de Bartter, le taux de la permeabilite passive du Na+ est eleve par rapport aux temoins, sans elevation toutefois du taux de la permeabilite passive du K+. Cette elevation du taux de la permeabilite passive du Na+ peut expliquer en partie les concentrations intra-erythrocytaires elevees de Na+ retrouvees chez nos patients. Quant aux autres systemes de transport, nos patients presentaient un taux maximal d'efiiux de Na+ sensible a la ouabaine legerement eleve et des flux des au co-transport variables. Les flux de Na+ et K+ chez les parents de patients etaient normaux.