Carroll P R, Nasveld P E
Aust J Exp Biol Med Sci. 1978 Aug;56(4):493-7. doi: 10.1038/icb.1978.55.
On the isolated, perfused rabbit ear artery methysergide 10(-9) mol.1(-1) only potentiated the constrictor response to serotonin while at a concentration of 2.5 x 10(-8) mol.1(-1) it only blocked the response. At an intermediate concentration (2.5 x 10(-9) mol.1(-1)) it produced initial potentiation followed by subsequent blockade. In contrast, at all three concentrations it only potentiated the constrictor response to noradrenaline. The results thus show that methysergide can exert a dual effect on the constrictor response to serotonin with the actual effect produced being dependent not only on the concentration of methysergide used but also on the period of time the artery is exposed to methysergide.
在离体灌注的兔耳动脉上，10⁻⁹摩尔/升的甲基麦角新碱仅增强了对5-羟色胺的收缩反应，而在2.5×10⁻⁸摩尔/升的浓度下，它仅阻断该反应。在中间浓度（2.5×10⁻⁹摩尔/升）时，它首先产生增强作用，随后是阻断作用。相比之下，在所有这三种浓度下，它仅增强了对去甲肾上腺素的收缩反应。因此，结果表明甲基麦角新碱对5-羟色胺的收缩反应可产生双重作用，实际产生的作用不仅取决于所用甲基麦角新碱的浓度，还取决于动脉暴露于甲基麦角新碱的时间。
