Anti-leukotriene D4 action of a new anti-asthmatic drug (KC-404) on the guinea-pig isolated trachea.

Anti-asthmatic drug, KC-404, inhibited specifically spontaneous contraction and leukotriene (LT) D4-induced contraction of guinea-pig trachea. Relaxation of spontaneous contraction by KC-404 was reduced by the treatment of the guinea-pig trachea with a cyclooxygenase inhibitor, flurbiprofen. Some parallel shift of the concentration-action curve of LTD4 by KC-404 was still observed in the presence of flurbiprofen. Specific binding of [3H]LTD4 to the microsomal fraction of guinea-pig trachea was partially inhibited by KC-404. These results suggest that the relaxing action of trachea of KC-404 is due to the interference of interaction between LTD4 and its receptor and to the product(s) via cyclooxygenase pathway.