[Preventive effect of a novel leukotrienes antagonist ONO-1078 on leukotriene C4- and D4-induced human bronchial smooth muscle contraction].

To study whether a novel leukotrienes antagonist ONO-1078 (4-oxo-8-[4-phenylbutyloxy) benzoylamino]-2-(tetrazol-5-yl)-4H-1-benzopyran hemihydrate) prevents leukotrienes C4- and D4-(LTC4, LTD4) induced human bronchial smooth muscle contraction, we examined the bronchial contractile response to LTC4 and LTD4 in the presence or in the absence of ONO-1078 in human bronchial strips. We prepared 4 strips from each of 5 patients undergoing lobectomy of the lung because of lung cancer. We mounted the strips in organ baths and measured the contractile response to LTC4 and LTD4 from 10(-11) M to 10(-7) M after incubation with ONO-1078 (10(-8) M, 10(-7) M and 10(-6) M) and without ONO-1078. ONO-1078 shifted the dose response curve to LTC4 to higher concentration in dose dependent fashion, and it significantly inhibited the contractile response to LTC4 and LTD4. In the presence of L-serine borate complex (45 mM), an inhibitor of gamma-glutamyl transpeptidase, ONO-1078 significantly inhibited the LTC4-induced contraction. On the other hand, ONO-1078 had no effect on the contractile response to acetylcholine. These results suggest that ONO-1078 is a specific antagonist of LTC4 and LTD4 receptors in human bronchial smooth muscle. Because the effect of LTC4 and LTD4 is thought to be an important part of the pathogenesis of bronchial asthma, our results also suggest that ONO-1078 may be a useful prophylactic drug for bronchial asthma.