Cardiovascular effects in the Sprague-Dawley rat of 8-hydroxy-2(di-N-propylamino) tetralin, a selective 5-hydroxytryptamine receptor agonist.

The intravenous administration of 8-hydroxy-2(di-N-propylamino) tetralin, a selective 5-HT receptor agonist, caused a biphasic blood pressure response and bradycardia in Sprague-Dawley rats. The initial pressor response involved peripheral alpha 1-adrenoceptors since it was present in pithed rats and was antagonized by prazosin. Though the intracerebroventricular route of administration was not more effective the hypotension and bradycardia were probably of central origin. The bradycardia was prevented by pretreatment with atropine and propranolol suggesting an involvement of vagal as well as sympathetic activity. These results support the view that central 5-HT receptor activation reduces the blood pressure and heart rate.