Salbutamol inhibits RhoA activation in normal but not in desensitized bronchial smooth muscle cells. (16th June 2015) - Fogli, Stefano
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. Key findings 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.