摘要：Background: Medicinal plants contain physiologically active principles that over the years have been exploited in traditional medicine for the treatment of various ailments. Objectives and Methods: This study aimed to investigate the effects of the methanolic extract of Pausinystalia yohimbe bark (5 mg/ml) on isolated rabbit aortic strip and rat uterus. Results: methanolic extract of P. yohimbe bark (5 mg/ml) produced relaxation of the phenylephrine precontracted-rabbit aortic strip. This relaxation may be resulted through nitric oxide (NO), since the pretreatment of the isolated rabbit aortic strip with methylene blue inhibited the NO-mediated relaxation. Moreover, the extract exhibited relaxation of rat uterine muscles, which appeared to be not mediated by activation of β2-adrenoceptors and/or H2 receptors, since the relaxant effect continued even after the pretreatment of the tissue with propranolol and ranitidine respectively. Conclusion: The obtained results revealed that methanolic extract of P. yohimbe bark caused relaxation of both isolated rat uterus and rabbit aortic strip through facilitating the role of endogenous compounds such as NO.
