Evaluation of the effect of Myrica sapida on bronchoconstriction and bronchial hyperreactivity.

The present investigation was undertaken to evaluate the bronchodilator and bronchial hyperreactivity of the stem bark of Myrica sapida. Experimental models studied were histamine induced bronchospasm in guinea pigs, bronchoalveolar lavage fluid (BALF) in egg albumin sensitized guinea pigs, histamine release from the lung tissues of sensitized guinea pigs and histopathological studies. Ethanolic extract of M. sapida (75 mg/kg, p.o., for 7 days) showed significant protection against histamine aerosol induced bronchospasm. Significant decrease in the total and differential leukocyte counts in BALF and prevention of egg albumin induced histamine release from chopped lung tissues of sensitized guinea pigs was observed on chronic administration of ethanolic extract of M. sapida (75 mg/kg, p.o., for 15 days). Histological examination of the section of lung from sensitized guinea pigs treated with ethanolic extract of M. sapida (75 mg/kg, p.o., for 15 days) was comparable to that of the control group. These results suggest that M. sapida possesses not only bronchodilator activity but also decreases bronchial hyperresponsiveness by decreasing the infiltration of inflammatory mediators like eosinophils, neutrophils in BALF and inhibiting histamine release from lungs of sensitized guinea pigs.