Effect of montelukast, MK-571, BAY u9773 and U-75302 on ACh-induced contraction in phenylephrine-precontracted rat thoracic aortic strips. Cumulative dose-response curves of antagonists were performed on rat thoracic aortic strips stretched to 0.7 g resting tension and preincubated with 5 μM indomethacin. Curves were statistically analysed using ALLFIT (Delean et al., 1978) and one-way ANOVA followed by Bonferroni's t-test. Values are the means±s.e.mean of at least four experiments. *P<0.05 vs montelukast, one-way ANOVA; § P<0.05 vs montelukast, MK-571 and BAY u9773, one- way ANOVA. For more details, see Results.