title: Intact rat superior mesenteric artery endothelium is an electrical syncytium and expresses strong inward rectifier K+ conductance.
abstract: OBJECTIVE
  Vascular endothelial and smooth muscle cell phenotypes may change dramatically after isolation and in cell cultures. This study was designed to investigate gap junctions coupling in an integrated intact preparation and to test if K(IR) channels modulate resting membrane conductance in "in situ" endothelial cells (EC), and acetylcholine (ACh)-evoked relaxation of the rat superior mesenteric artery.
  
  
  METHODS
  Whole cell blind patch recordings of ionic currents from in situ EC, dye-coupling experiments, and functional studies were performed in rat superior mesenteric artery.
  
  
  RESULTS
  EC were dye-coupled through gap junctions. 18β-glycyrretinic acid (25 μM) decreased outward and inward currents, the 80% decay of time and time constant of the capacitative transients, capacitance, and increased input resistance. Barium chloride (30 μM) decreased resting and ACh-evoked inward currents, the sensitivity of ACh-evoked relaxation, and decreased both the sensitivity and the maximal relaxation to S-nitroso-N-acetyl penicillamine in arteries with, but not in arteries without endothelium.
  
  
  CONCLUSIONS
  The present results suggest that the EC layer of this large artery is electrically coupled, and that K(IR) channels regulate resting inward conductance, hence suggesting that they are of importance for resting membrane potential in in situ EC. Moreover, EC K(IR) channels are involved in ACh-evoked relaxation.
authors.affiliation: Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain. bcliment@farm.ucm.es
authors.forename: Belén
authors.initials: B
authors.lastname: Climent
authors.forename: Emese
authors.initials: E
authors.lastname: Zsiros
authors.forename: Edgaras
authors.initials: E
authors.lastname: Stankevicius
authors.forename: Pedro
authors.initials: P
authors.lastname: de la Villa
authors.forename: György
authors.initials: G
authors.lastname: Panyi
authors.forename: Ulf
authors.initials: U
authors.lastname: Simonsen
authors.forename: Albino
authors.initials: A
authors.lastname: García-Sacristán
authors.forename: Luis
authors.initials: L
authors.lastname: Rivera
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004553:Electric Conductivity; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D017629:Gap Junctions / Q000502:physiology*; D015726:Giant Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D008638:Mesenteric Arteries / Q000166:cytology*; D024661:Potassium Channels, Inwardly Rectifying / Q000502:physiology*; D051381:Rats; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology
chemical_list: D024661:Potassium Channels, Inwardly Rectifying; D026423:S-Nitroso-N-Acetylpenicillamine; D000109:Acetylcholine