ANTAGONISM OF LEUKOTRIENE RESPONSES IN HUMAN AIRWAYS BY BAY X7195

Contractions induced by leukotriene and anti-IgE (sheep antiserum to h uman IgE) were antagonized by pretreatment of human airways with the c ysteinyl leukotriene receptor antagonist BAY x7195 o]-7-[4-(4-phenoxyb utoxy)-phenyl]-hept-5-(z)-enoic acid). However, this receptor antagoni st did not inhibit either leukotriene D-4- or leukotriene C-4-induced contractions in human pulmonary veins. The pA(2) value for BAY x7195 i n human airways against leukotriene D-4 was 7.83 +/- 0.16 with a slope of 1.07 +/- 0.15 (means +/- S.E.M; n = 11). The IC50 value for BAY x7 195 in human airways contracted with anti-IgE was 0.31 +/- 0.08 mu M ( n = 11). These results were comparable to those obtained with ICI 204, 219 3-ylmethyl)-3-methoxy-N-otolyl-sulfonylbenzamide). These data demo nstrate that BAY x7195 is a potent selective leukotriene receptor anta gonist which may block allergic reactions in the lung.