Abstract:
OBJECTIVE To observe the effect of PDE4 inhibitor(roflumilast) and 5-lipoxygenase inhibitor(zileuton) on the contraction of airway smooth muscle of asthma rat, and try to discuss their pharmacologic action on airway smooth muscle.
METHODS Asthmatic and normal rats were executed for the airway smooth muscle strips. Gradual cumulative dose of acetylcholine(Ach) was used to study the contraction of muscle strips. Roflumilast or zileuton gradient cumulative administration or pre-incubation were used to study their diastolic and contractile function of muscle strips. Tension transducer, biological signal collecting system were used to record changes under various treatments.
RESULTS Ach(10
-8-10
-3 mol·L
-1) could induce the contraction of airway smooth muscle of asthma rat and normal rat, there were no significant difference. The maximal contraction of smooth muscle was induced by Ach, and the sensitivity of airway smooth muscle to roflumilast in asthmatic rats after cumulative dose administration was higher than normal rats, while the sensitivity of airway smooth muscle to zileuton in asthmatic rats was less sensitive than that of normal rats. Using roflumilast pre-incubation and cumulative administration of the constrictor Ach(10
-8-10
-3 mol·L
-1), there was no significant difference in the reactivity of airway smooth muscle for Ach between normal rats and asthmatic rats. But pre-incubated with zileuton, after the cumulative administration of Ach (10
-8-10
-3 mol·L
-1), the reactivity of airway smooth muscle of asthmatic rats for Ach was more significant than that of normal rats.
CONCLUSION Roflumilast can inhibit the contraction of airway smooth muscle of asthma rats. However, zileuton has no obvious inhibitory effect on the contraction of asthmatic airway smooth muscle and may induce airway hyperresponsiveness.