PT - JOURNAL ARTICLE AU - Hiroyasu Sakai AU - Yoshihiko Chiba AU - Tomona Hirano AU - Miwa Misawa TI - Possible Involvement of CPI-17 in Augmented Bronchial Smooth Muscle Contraction in Antigen-Induced Airway Hyper-Responsive Rats AID - 10.1124/mol.104.004325 DP - 2005 Jul 01 TA - Molecular Pharmacology PG - 145--151 VI - 68 IP - 1 4099 - http://molpharm.aspetjournals.org/content/68/1/145.short 4100 - http://molpharm.aspetjournals.org/content/68/1/145.full SO - Mol Pharmacol2005 Jul 01; 68 AB - Airway hyper-responsiveness (AHR) associated with heightened airway resistance and inflammation is a characteristic feature of asthma. It has been demonstrated that contractile responsiveness and Ca2+ sensitization to acetylcholine (ACh) in repeated antigen challenge-induced airway hyper-responsive bronchial preparation were significantly increased. The CPI-17 (PKC-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase of 17 kDa) is activated by protein kinase C and acts on a myosin light-chain phosphatase-specific target. The aim of the present study was to explore the role of CPI-17 in hyper-responsiveness of bronchial smooth muscle in antigen-induced AHR rats. In immunoblotting, the levels of expression of CPI-17 mRNA and protein were significantly increased in bronchus from rats that were repeatedly challenged with antigen. ACh-induced CPI-17 phosphorylation and translocation to membrane fraction were also significantly increased in bronchus from antigen-challenged rats. In conclusion, we suggest that augmented expression and activation of CPI-17 observed in the hyper-responsive bronchial smooth muscle might be responsible for the enhanced ACh-induced Ca2+ sensitization of bronchial smooth muscle contraction associated with AHR.