title: Salbutamol inhibits RhoA activation in normal but not in desensitized bronchial smooth muscle cells.
abstract: OBJECTIVE
  This study was aimed at investigating whether the β2 -adrenoceptor agonist, salbutamol, could modulate RhoA activation in normal and homologously desensitized bronchial smooth muscle cells (BSMC).
  
  
  METHODS
  Serum-starved BSMCs were stimulated with the Rho-activating compound calpeptin in the presence or absence of salbutamol, the Epac activator, 8-pCPT-2'-O-Me-cAMP, or the site-selective activator of cAMP-dependent protein kinase A (PKA), 6-Bnz-cAMP. Activated RhoA was assessed by immunocytochemical detection and by RhoA G-LISA assay.
  
  
  RESULTS
  Stimulation with calpeptin caused translocation of RhoA from cytosol to plasma membrane, a condition required for the functional coupling of RhoA with its cellular targets. Pretreatment with salbutamol 10 μm for 15 min was found to block calpeptin-induced activation of RhoA in normal, but not in homologously desensitized cells. Pretreatment of calpeptin-stimulated BSMC with 8-pCPT-2'-O-Me-cAMP or 6-Bnz-cAMP could reproduce the effect of salbutamol.
  
  
  CONCLUSIONS
  These findings demonstrated that salbutamol inhibits RhoA activation in human BSMC through β2 -adrenoceptor/Epac/PKA pathway. An important pharmacological implication of these finding is the possible contribution of RhoA pathway to the molecular mechanism involved in airway smooth muscle relaxation caused by acute/chronic exposure to β2-adrenoceptor agonists.
authors.affiliation: Department of Pharmacy, University of Pisa, Pisa, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Fogli
authors.affiliation: Department of Pharmacy, University of Pisa, Pisa, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Stefanelli
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Battolla
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Bianchi
authors.affiliation: Department of Pharmacy, University of Pisa, Pisa, Italy.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Breschi
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: Letizia
authors.initials: L
authors.lastname: Mattii
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000420:Albuterol / Q000008:administration & dosage / Q000494:pharmacology*; D001980:Bronchi / Q000166:cytology / Q000187:drug effects*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004151:Dipeptides / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: C473217:8-(4-chloro-phenylthio)-2'-O-methyladenosine-3'-5'-cyclic monophosphate; D058666:Adrenergic beta-2 Receptor Agonists; D004151:Dipeptides; C071482:calpeptin; D000242:Cyclic AMP; D020742:rhoA GTP-Binding Protein; D000420:Albuterol
keywords: RhoA; airway smooth muscle cells; salbutamol; β2-adrenoceptors