title: High conductance potassium channels activation by acid exposure in rat aorta is endothelium-dependent.
abstract: BACKGROUND
  We investigated, previously, the mechanism by which extracellular acidification promotes relaxation in rat thoracic aorta. These studies suggested that extracellular acidosis promotes vasodilation mediated by NO, KATP and SKCa, and maybe other K(+) channels in isolated rat thoracic aorta. This study was carried out to investigate the paxilline-mediated hyperpolarization induced by acid exposure.
  
  
  RESULTS
  The relaxation response to HCl-induced extracellular acidification (7.4-6.5) was measured in rat aortic rings pre-contracted with phenylephrine (PE, 10(-6) M). The vascular reactivity experiments were performed in endothelium-intact and denuded rings, in the presence of paxilline (10(-6) M), which is an inhibitor of high calcium conductance potassium BKCa channels. In rings with endothelium, paxilline inhibits relaxation, triggered by acidification at all pH values lower than 7.2 and had no effect on rings without endothelium, showing that the activation of BKCa is endothelium-dependent.
  
  
  CONCLUSIONS
  High conductance potassium channel activation induced by acid exposure is endothelium-dependent.
authors.affiliation: Department of Surgery and Anatomy, Laboratory of Endothelial Function, School of Medicine, University of São Paulo, Av. Café, 3000, Ribeirão Preto, SP, Brazil. acarla_c@yahoo.com.
authors.forename: Andrea Carla
authors.initials: AC
authors.lastname: Celotto
authors.affiliation: Department of Surgery and Anatomy, Laboratory of Endothelial Function, School of Medicine, University of São Paulo, Av. Café, 3000, Ribeirão Preto, SP, Brazil. verenacapellini@ig.com.br.
authors.forename: Verena Kise
authors.initials: VK
authors.lastname: Capellini
authors.affiliation: Department of Surgery and Anatomy, Laboratory of Endothelial Function, School of Medicine, University of São Paulo, Av. Café, 3000, Ribeirão Preto, SP, Brazil. agnes@fmrp.usp.br.
authors.forename: Agnes Afrodite Sumarelli
authors.initials: AA
authors.lastname: Albuquerque
authors.affiliation: Department of Surgery and Anatomy, Laboratory of Endothelial Function, School of Medicine, University of São Paulo, Av. Café, 3000, Ribeirão Preto, SP, Brazil. luciana_garros@yahoo.com.br.
authors.forename: Luciana Garros
authors.initials: LG
authors.lastname: Ferreira
authors.affiliation: Department of Surgery and Anatomy, Laboratory of Endothelial Function, School of Medicine, University of São Paulo, Av. Café, 3000, Ribeirão Preto, SP, Brazil. ap_silveira@yahoo.com.br.
authors.forename: Ana Paula Cassiano
authors.initials: AP
authors.lastname: Silveira
authors.affiliation: Department of Surgery and Anatomy, Laboratory of Endothelial Function, School of Medicine, University of São Paulo, Av. Café, 3000, Ribeirão Preto, SP, Brazil. talesusp@yahoo.com.br.
authors.forename: Tales Rubens
authors.initials: TR
authors.lastname: de Nadai
authors.affiliation: Department of Surgery and Anatomy, Laboratory of Endothelial Function, School of Medicine, University of São Paulo, Av. Café, 3000, Ribeirão Preto, SP, Brazil. prbevora@gmail.com.|, Av. Bandeirantes, 3900, HC-FMRP, 9o. andar, Ribeirão Preto, SP, 14.049-900, Brazil. prbevora@gmail.com.
authors.forename: Paulo Roberto Barbosa
authors.initials: PR
authors.lastname: Evora
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism*; D006851:Hydrochloric Acid / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism*; D051381:Rats; D014664:Vasodilation / Q000502:physiology*
chemical_list: D007211:Indoles; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C048220:paxilline; D006851:Hydrochloric Acid