Red blood cell sodium transport and phosphate release in uremia.
Red blood cell (RBC) phosphate release was linear for more than 1 h and dependent on the intracellular hydrolysis of organic phosphate esters. In uremics on chronic hemodialysis total phosphate release was significantly increased suggesting an elevated RBC energy metabolism. Ouabain-sensitive phosphate release, however, was decreased. For RBCs of controls and uremic subjects approximately 80% of inorganic phosphate liberated within the cell was recycled. Thus, RBC phosphate release represents 20% of intracellular phosphate ester metabolism. In uremia active electrolyte transport was diminished, suggesting an impaired Na-K-ATPase activity. It resulted in an increased RBC sodium and a decreased potassium concentration. The positive correlation between ouabain-sensitive rate constant for sodium efflux and ouabain-sensitive RBC phosphate release indicates that ouabain inhibition of phosphate elimination might be related to Na-K-ATPase. In RBCs of uremic subjects almost 4% of the increased energy metabolism was needed for active electrolyte transport mechanisms, in control RBCs 12% was required.
D001693:Biological Transport, Active; D004734:Energy Metabolism; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels; D010042:Ouabain / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D006435:Renal Dialysis; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014511:Uremia / Q000378:metabolism* / Q000628:therapy
D007473:Ion Channels; D010710:Phosphates; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium