Oriowo M A
Arch Int Pharmacodyn Ther. 1981 Nov;254(1):13-9.
The contractile effect of 5-hydroxytryptamine on the rat isolated anococcygeus muscle was analysed. 5-Hydroxytryptamine (10(-6) g ml-1 - 1.6 X 10(-5) g ml-1) concentration-dependently contracted the anococcygeus muscle. The contractions were not competitively antagonized by methysergide (2.5 X 10(-8) g ml-1 - 10(-6) g ml-1) as the contractile response to higher concentrations of 5-hydroxytryptamine were not much reduced. The methysergide-resistant contractions to 5-hydroxytryptamine were not reduced by hyoscine (6 X 10(-7) g ml-1), tetrodotoxin (2 X 10(-7) g ml-1), but were completely abolished by phentolamine (3 X 10(-7) g ml-1). 5-Hydroxytryptamine-induced contractions were considerably reduced but not completely abolished by reserpinization. It is suggested that 5-hydroxytryptamine contracted the rat anococcygeus muscle directly (by activating tryptaminergic 'D' receptors) and indirectly by releasing noradrenaline at the nerve endings.
分析了5-羟色胺对大鼠离体肛尾肌的收缩作用。5-羟色胺（10⁻⁶ g/ml - 1.6×10⁻⁵ g/ml）能使肛尾肌产生浓度依赖性收缩。麦角新碱（2.5×10⁻⁸ g/ml - 10⁻⁶ g/ml）对这些收缩无竞争性拮抗作用，因为较高浓度的5-羟色胺引起的收缩反应并未大幅降低。对5-羟色胺产生的麦角新碱抵抗性收缩不受东莨菪碱（6×10⁻⁷ g/ml）、河豚毒素（2×10⁻⁷ g/ml）的影响，但可被酚妥拉明（3×10⁻⁷ g/ml）完全消除。5-羟色胺诱导的收缩在利血平化后明显减弱但未完全消除。提示5-羟色胺直接（通过激活色胺能“D”受体）和间接（通过在神经末梢释放去甲肾上腺素）使大鼠肛尾肌收缩。
