title: Study of erythrocyte ATPases in infants evaluated during the recovery phase of severe dehydration caused by diarrhea.
abstract: OBJECTIVE
  Patients severely dehydrated from diarrhea are at risk of developing hyperkalemia consequent to fluid therapy treatment. In parallel with the regulation of external potassium balance by the kidney and gastrointestinal tract, plasma potassium is rapidly regulated by redistribution of potassium between the extracellular and intracellular compartments. Erythrocytes contain ATPases that play a role in this potassium movement. In this study, erythrocyte ATPase effectiveness was evaluated in infants dehydrated from diarrhea and compared to that of healthy infants.
  
  
  METHODS
  Blood samples were collected from dehydrated and healthy infants. The activity of Na+,K+-ATPase and of an ouabain-insensitive K+-ATPase were assessed. Serum electrolytes and blood pH were also determined.
  
  
  RESULTS
  No hyperkalemia was found, even in dehydrated infants presenting with severe hyperchloremic metabolic acidosis. In the erythrocytes of dehydrated infants, Na+,K+-ATPase activity was increased correlating positively with the amount of sodium administered. High K+-ATPase activity in the erythrocytes correlated with low plasma potassium. The K+-ATPase activity correlated positively with the amount of potassium administered to dehydrated infants.
  
  
  CONCLUSIONS
  These findings suggest that the erythrocytes Na+,K+-ATPase and K+-ATPase both protect against plasma potassium abnormalities in dehydrated infants. In such infants, the risk of hyperkalemia is probably low.
authors.affiliation: Instituto da Criança, Departamento de Pediatria, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: José Nélio
authors.initials: JN
authors.lastname: Cavinatto
authors.forename: Magali
authors.initials: M
authors.lastname: de Araujo
authors.forename: Antonio Carlos
authors.initials: AC
authors.lastname: Seguro
authors.forename: Francisco Roque
authors.initials: FR
authors.lastname: Carrazza
authors.forename: Claudia Maria Barros
authors.initials: CM
authors.lastname: Helou
mesh_terms: D000138:Acidosis / Q000209:etiology; D002675:Child, Preschool; D003681:Dehydration / Q000188:drug therapy / Q000201:enzymology* / Q000209:etiology; D003967:Diarrhea / Q000150:complications*; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D006801:Humans; D008297:Male; D011188:Potassium / Q000097:blood* / Q000627:therapeutic use; D012964:Sodium / Q000378:metabolism / Q000627:therapeutic use; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
chemical_list: D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium