title: Age-dependent effect of ouabain on renal Na+,K+-ATPase.
abstract: OBJECTIVE
  This study examines the effect of chronic ouabain-treatment on renal Na(+) handling in 12-week and 52-week old rats.
  
  
  METHODS
  Wistar Kyoto rats aged 5 weeks or 45 weeks were treated with ouabain or vehicle during 7 weeks. Blood pressure was measured in conscious animals throughout the study. After 7 weeks of treatment urinary electrolyte concentration, Na(+),K(+)-ATPase activity and α(1)-subunit expression were determined in 12-week and 52-week old rats.
  
  
  RESULTS
  In 12-week and 52-week old rats ouabain produced a significant increase in systolic blood pressure. Although no differences were observed in Na(+) excretion in these animals, 12-week old ouabain-treated rats had lower Na(+),K(+)-ATPase activity in proximal tubules. However, 12-week old ouabain-treated rats had decreased fractional excretion of Na(+). In proximal tubules of 52-week old rats Na(+),K(+)-ATPase activity did not differ between vehicle and ouabain-treated groups.
  
  
  CONCLUSIONS
  Our results show that in Wistar Kyoto rats renal response to ouabain treatment may be age-dependent and that the hypertensive effect of ouabain is independent of the effect on renal Na(+),K(+)-ATPase.
authors.affiliation: Institute of Pharmacology & Therapeutics, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal.
authors.forename: E
authors.initials: E
authors.lastname: Silva
authors.forename: M P
authors.initials: MP
authors.lastname: Serrão
authors.forename: P
authors.initials: P
authors.lastname: Soares-da-Silva
mesh_terms: D000367:Age Factors; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002316:Cardiotonic Agents / Q000494:pharmacology*; D006973:Hypertension / Q000139:chemically induced*; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D008297:Male; D010042:Ouabain / Q000494:pharmacology*; D051381:Rats; D011921:Rats, Inbred WKY; D012964:Sodium / Q000652:urine; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects* / Q000378:metabolism
chemical_list: D002316:Cardiotonic Agents; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase