Sodium, potassium and osmolality of human and canine erythrocytes--interest of trapped plasma and water content for their full significance

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.

Red blood cell sodium content and permeability changes in hemorrhagic shock

Recent studies of cellular function have demonstrated significant alterations of cell homeostasis during hemorrhagic shock. The progressive depolarization of cell membranes demonstrated in several organs has been attributed to failure of energy-dependent active ion transport. Similar changes in intracellular electrolyte composition have been observed in the red blood cells of some patients in late hemorrhagic shock and in other severely ill patients. The ready availability of isolated cells that do not require extracellular fluid space assessment makes the red blood cell an attractive model for investigating the factors controlling ion movements across the cell wall. It has been suggested that the red blood cell ion abnormalities may represent a generalized cellular response to severe illness. Red blood cell sodium concentration was measured in 145 patients during severe hemorrhagic shock. The direction and magnitude of changes in red blood sodium concentration was correlated with the time course of the shock state. The initial decrease in sodium content was a function of the diminished red blood cell membrane permeability due to a decrease in plasma bicarbonate levels. The subsequent red blood cell sodium uptake above the normal range, not associated with an increase in sodium influx, indicated an impairment of energy-dependent active transport. The observed high sodium concentrations associated with a potassium decrease in the red blood cell appeared to be only one manifestation of a generalized defect in cellular function and composition during severe hemorrhagic shock.