title: Contribution of the amiloride-sensitive component and the Na+/H+ exchanger to renal responsiveness to vasoconstrictors.
abstract: OBJECTIVE
  This study analyzed the role of the amiloride-sensitive component and the participation of the Na(+)/H(+) exchanger in renal responsiveness to vasoconstrictors in the isolated perfused rat kidney.
  
  
  METHODS
  The renal responses to vasoconstrictors (angiotensin II, phenylephrine, vasopressin and KCl) were studied under baseline conditions and after the administration of amiloride (10 and 100 μmol/l) or the specific Na(+)/H(+) exchange inhibitor ethylisopropylamiloride (EIPA, 10 μmol/l). The effects of amiloride and EIPA on renal responsiveness to vasoconstrictors were also analyzed in endothelium-denuded preparations.
  
  
  RESULTS
  Amiloride reduced renal responsiveness to all vasoconstrictors in a dose-related manner, whereas EIPA did not affect the renal pressor response to KCl. The inhibitory effects of amiloride and EIPA on renal responsiveness to vasoconstrictors persisted after endothelium removal.
  
  
  CONCLUSIONS
  These results indicate that the amiloride-sensitive component and the Na(+)/H(+) exchanger play an important role in responsiveness to the main endogenous vasoconstrictors in the renal vasculature. These results also suggest that amiloride might be useful as an inhibitor of renal vasoconstriction, even in diseases with endothelial dysfunction.
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de Granada, Granada, Spain. fvargas@ugr.es
authors.forename: Pablo
authors.initials: P
authors.lastname: Vargas
authors.forename: Rosemary
authors.initials: R
authors.lastname: Wangensteen
authors.forename: Isabel
authors.initials: I
authors.lastname: Rodríguez-Gómez
authors.forename: Rocío
authors.initials: R
authors.lastname: Perez-Abud
authors.forename: Antonio
authors.initials: A
authors.lastname: Osuna
authors.forename: Andrés
authors.initials: A
authors.lastname: Quesada
authors.forename: Félix
authors.initials: F
authors.lastname: Vargas
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D004232:Diuretics / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007668:Kidney / Q000098:blood supply / Q000187:drug effects* / Q000502:physiology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D026941:Sodium Channel Blockers / Q000494:pharmacology*; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors* / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D004232:Diuretics; D026941:Sodium Channel Blockers; D017923:Sodium-Hydrogen Exchangers; D014662:Vasoconstrictor Agents; D000584:Amiloride; C039614:ethylisopropylamiloride