Met-enkephalin effects on histamine-induced bronchoconstriction in guinea pigs

We investigated the effects of the neuropeptide met-enkephalin on histamine-induced bronhoconstriction in an experimental model of asthma. Classic Konzett and Rossler's method of whole body plethysmography modified by Gjuris(1), was applied in the study. This method represents a standard experimental model of bronchoconstriction, suitable for the evaluation of peptide effects on the histamine-induced bronchoconstriction. The results of the measurements implicate a dose-related modulatory effect of met-enkephalin on the bronchoconstrictor action of histamine. Met-enkephalin doses of 1 mg/kg and 10 mg/kg, respectively, caused statistically significant reduction of the histamine-induced bronchoconstriction. Estimated ED50 dose was 0.235 mg/kg. Further studies are needed to define practical and therapeutical use of the presented observations in respiratory pharmacology.