Bronchodilator activity of an aqueous fraction of an ethanol extract of the leaves of Cissampelos sympodialis Eichl. (Menispermaceae) in the guinea pig.

The bronchodilator activity of an aqueous fraction (AF) of a 70% hydroalcoholic extract of the leaves of Cissampelos sympodialis Eichl. was evaluated in the guinea-pig. The AF inhibited the spontaneous tone of the trachea (IC(50), 13.9 μg/ml), which was potentiated (IC(50), 4.6 μg/ml) by 3-isobutyl-l-methylxanthine, blocked by β(2) adrenoceptor blocking agent timolol, but unaffected by removal of epithelium or addition of NG-Nitro-L-arginine methyl ester or methylene blue. The AF also antagonized contractions induced by carbachol, capsaicin and arachidonic acid in normal trachea and by ovalbumin in trachea obtained from sensitized guinea-pigs. The IC(50)-values in these experiments varied from 34.1-70.5 μg/ml. Further, the AF (100 mg/kg) by the more effective i.p. route increased the preconvulsive time of animals exposed to an aerosol of histamine to 63.5 ± 5 s 1 h after administration compared to 28 ± 1 s in the untreated group. In addition, the AF at 100 mg/kg i.p. or i.G. protected the sensitized guinea-pigs against anaphylactic shock induced by ovalbumin aerosol by 78.6 and 86.7% respectively.