Abstract

Dihydroergotoxine (0.01-0.3 mg kg-1 i.v.) decreased heart rate in pentobarbitone-anaesthetized rats. The bradycardia was reduced but not blocked by pre-treatment with guanethidine, yohimbine, propranolol or pithing. It was not prevented by bivagotomy, atropine, sulpiride or haloperidol. Dihydroergotoxine failed to affect, either the bradycardia produced by electrical stimulation of the vagus, or the cardioacceleration induced by i.v. isoprenaline. The increase in heart rate elicited in pithed rats by electrical stimulation of the spinal cord was reduced by dihydroergotoxine; this effect being inhibited by yohimbine but not by sulpiride. In conclusion, the main mechanism by which dihydroergotoxine (i.v.) induces bradycardia in the rat involves stimulation of alpha 2-adrenoceptors located predominantly at the cardiac sympathetic nerve endings.

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 call

Disclaimer: 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.