Abstract
The present study investigates the mechanism(s) of action of relaxations induced by bradykinin and by electrical field stimulation (EFS) in isolated rat anococcygeus muscle, where contractile tone has been elevated with clonidine. Bradykinin, EFS, and the bradykinin B 1 receptor agonist, des-Arg 9-bradykinin, produced quantitatively and qualitatively similar relaxations. Bradykinin B 1 receptor antagonist, [des-Arg 9, Leu 8]-bradykinin (1 μM), attenuated the relaxation responses of bradykinin B 1 receptor agonist and inhibited bradykinin and EFS-induced relaxation responses. Bradykinin B 2 receptor antagonist, [β-(2-thienyl)-Ala 5,8, D-Phe]-bradykinin (1 μM), significantly inhibited the relaxation responses of bradykinin, EFS, and bradykinin B 1 receptor agonist. Methylene blue (30 μM) and N-methylhydroxylamine (1 mM) significantly inhibited the bradykinin- and EFS-induced relaxation responses. The relaxation responses of bradykinin and EFS were not affected by captopril (5 μM), superoxide dismutase (100 U/ml), and catalase (100 U/ml). Nitric oxide synthase inhibitor, L-N G-nitro-arginine (L-NOARG, 30 μM), significantly inhibited the EFS- and bradykinin-induced relaxation responses. L-arginine (100 μM) reversed the inhibitory effect of L-NOARG on the relaxation responses of EFS and bradykinin. In addition, L-arginine potentiated the relaxation responses of EFS and bradykinin. The data of the present study suggests that bradykinin, similar to EFS, generates an endogenous nitrate, probably nitric oxide, which subsequently activates guanylate cyclase and relaxes the rat anococcygeus muscle.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
