Regulation of the cystic fibrosis transmembrane conductance regulator channel by beta-adrenergic agonists and vasoactive intestinal peptide in rat smooth muscle cells and its role in vasorelaxation.
The signaling events that regulate vascular tone include voltage-dependent Ca(2+) influx and the activities of various ionic channels; which molecular entities are involved and their role are still a matter of debate. Here we show expression of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel in rat aortic smooth muscle cells. Immunoprecipitation and in vitro protein kinase A phosphorylation show the appearance of mature band C of CFTR. An immunohistochemistry study shows CFTR proteins in smooth muscles of aortic rings but not in skeletal muscles. Using the iodide efflux method, a combination of agonists and pharmacological agents was used to dissect the function of CFTR. Agonists of the cAMP pathway, the beta-adrenergic agonist isoproterenol, and the neuropeptide vasoactive intestinal peptide activate CFTR-dependent transport from cells maintained in a high but not low extracellular potassium-rich saline, suggesting that depolarization of smooth muscle is critical to CFTR activation. Smooth muscle CFTR possesses all of the pharmacological attributes of its epithelial homologues: stimulation by the CFTR pharmacological activators MPB-07 (EC(50) = 158 microm) and MPB-91 (EC(50) = 20 microm) and inhibition by glibenclamide and diphenylamine-2-carboxylic acid but not by 5,11,17,23-tetrasulfonato-25,26,27,28-tetramethoxy-calix[4]arene. Contraction measurements on isolated aortic rings were performed to study the contribution of CFTR to vascular tone. With aortic rings (without endothelium) preconstricted by high K(+) saline or by the alpha-adrenergic agonist norepinephrine, CFTR activators produced a concentration-dependent relaxation. These results identify for the first time the expression and function of CFTR in smooth muscle where it plays an unexpected but fundamental role in the autonomic and hormonal regulation of the vascular tone.
Robert
Renaud
R
Laboratoire des Biomembranes et Signalisation Cellulaire CNRS Unité Mixte de Recherche 6558, Université de Poitiers, 86022 Poitiers, France.
Thoreau
Vincent
V
Norez
Caroline
C
Cantereau
Anne
A
Kitzis
Alain
A
Mettey
Yvette
Y
Rogier
Christian
C
Becq
Frédéric
F
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic; D002460:Cell Line; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000502:physiology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007454:Iodides / Q000378:metabolism; D007700:Kinetics; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology*
D000318:Adrenergic beta-Agonists; C505032:CFTR protein, human; D018118:Chloride Channels; D007454:Iodides; D014665:Vasodilator Agents; D000804:Angiotensin II; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D014660:Vasoactive Intestinal Peptide; D009638:Norepinephrine