Abstract: AIM: To investigate the antiasthmatic effects of novel K_ATP CO iptakalim on airway hyperresponsiveness and remodeling in guinea-pigs with asthma. METHODS: Thirty guinea-pigs were randomly assigned to five groups:control group, asthma group, iptakalim 0.75 group (asthmatic guinea-pigs treated with iptakalim 0.75 mg°kg^-1°d^-1, ig), iptakalim 1.5 group (asthmatic guinea-pigs treated with iptakalim 1.5 mg°kg^-1°d^-1, ig), and dexamethasone (Dex)group.The reactivity of tracheal stripe in various concentrations of histamine was measured.The airway internal perimeter, wall area and bronchial smooth muscle thickness were measured by image analysis system in all groups.RESULTS: The sensitivity of tracheal stripe to histamine was significantly higher in asthma group than that in the control group.Both doses of iptakalim could markedly reduce responsiveness of tracheal stripe to the histamine.The airway wall thickness (WA/PI) in asthmatic group (29.8±4.5 μm²°μm^-1)was significantly higher than that in the control group (13.2±5.7 μm²°μm^-1, P<0.01).The bronchial smooth muscle thickness in asthmatic group (11.7±4.7 μm²°μm^-1)was significantly higher than that in the control group (4.4±2.1 μm2·μm-1, P<0.05).The airway wall thickness (WA/PI)and bronchial smooth muscle thickness in the two iptakalim groups were increased slightly compared with these in the control group, but there were no significantly differences between them in statistic (P>0.05).CONCLUSION: iptakalim can reduce the airway hyperresponsiveness and remodeling in guinea-pigs with asthma.

Key words: ATP-sensitive potassiumchannel, iptakalim, asthma, airway hyperresponsiveness, airway remodeling