Experiments were designed to determine the effect of Mangifera indica Linn stem bark aqueous extract on rat trachea previously incubated in presence of indomethacin, propranolol, and atropine or promethazine with histamine or acetylcholine as agonist. The strips of trachea were suspended for isometric tension recording at 37 C. M. indica aqueous extract at 2 mg=ml impair the contraction induced both by histamine and acetylcholine in all three experimental conditions. The contractile responses

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... maximum effect) induced by histamine at 12 Â 10 À4 g=ml, in the presence of extract, were respectively 69.18 AE 3.05% (indomethacin), 74.18 AE 1.03% (indomethacin þ propranolol), and 45.54 AE 1.7% (indomethacinþpropranololþatropine) versus 100 AE 5.15% for control. The extract also reduced the contraction induced by acetylcholine, but this inhibitory effect is lightly decreased when the tissues were contracted by acetylcholine after incubation in presence of indomethacin þ propranolol. These experiments suggest that the aqueous extract of M. indica could block both the histaminic and muscarinic receptors on rat trachea; and the results corroborate with the traditional use of M. indica stem bark in the treatment of asthma.