Objective:To investigate the activity of the active principle in the spines of the seed pods of Mucuna pruriens using contraction of guinea pig ileum as index of pharmacological activity. Methods:The active principle was extracted with 0.0015 M NaCl.Muscle strips of guinea pig ileum were prepared and contractile responses were measured using a Kymograph.Two sets of experiment were conducted:（1）.The contraction of the ileum in presence of different concentrations of histamine,2-methylhistamine and the extract of Mucuna pruriens.（2）.The contractile response of the ileum in presence of different concentrations of the extract and antagonists including diphenhydramine,atropine and methysergide.Results:（1） The extract of Mucuna pruriens hair, 2- methylhistamine and histamine produced dose dependent contraction of guinea pig ileum (Extract ED50 = 13.0μg/mL,2-methylhistamine ED50=8.5μg/mL and histamine ED50=10.0μg/ mL).（2） Diphenhydramine,an H,antagonist competitively blocked the contractile response of the Mucuna pruriens extract（3） Coadminstration of the Mucuna pruriens extract either with different doses of antimuscarinic agent atropine or 5-hydroxytryptamine blocking agent methysergide did not alter the extract induced contractile response of the guinea pig ileum.Conclusion:These results demonstrate that the spines of Mucuna pruriens possess histamine activity which may contribute to its itching and painful irritation effects.
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