Antonaccio M J, Coté D
Eur J Pharmacol. 1976 Apr;36(2):451-4. doi: 10.1016/0014-2999(76)90101-1.
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.
甲基麦角新碱可使未麻醉的自发性高血压大鼠（SHR）的收缩压和心率呈剂量依赖性降低，而赛庚啶则无效。在用甲基麦角新碱或赛庚啶预处理的脊髓横断SHR中，对5-羟色胺（5-HT）的升压反应被消除。甲基麦角新碱对交感神经刺激的反应无改变，而赛庚啶则使其略有降低。两种药物均增强了对去甲肾上腺素的升压反应。未能确定甲基麦角新碱降压作用的外周机制表明，其作用可能是由中枢介导的，但并非依赖于5-羟色胺受体阻断。
