Centrally mediated antihypertensive and bradycardic effects of methysergide in spontaneously hypertensive rats.
Methysergide caused dose-dependent reductions in systolic blood pressure and heart rate of unanesthetized SHR, whereas cyproheptadine was ineffective. In pithed SHR pretreated with methysergide or cyproheptadine, pressor responses to 5-HT were abolished. Responses to sympathetic nerve stimulation were unaltered by methysergide, whereas cyproheptadine slightly reduced them. Both drugs enhanced pressor responses to norepinephrine. Failure to identify a peripheral mechanism for the antihypertensive action of methysergide suggests that the effect may be centrally mediated but not reliant upon serotonin receptor blockade.
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D003533:Cyproheptadine / Q000494:pharmacology; D003864:Depression, Chemical; D006339:Heart Rate / Q000187:drug effects*; D006973:Hypertension / Q000503:physiopathology*; D008784:Methysergide / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D014439:Tyramine / Q000494:pharmacology
D000959:Antihypertensive Agents; D003533:Cyproheptadine; D012701:Serotonin; D009638:Norepinephrine; D014439:Tyramine; D008784:Methysergide