三甲硫吩是一种直接作用的动脉血管扩张剂和α-肾上腺素能受体拮抗剂。

Trimethaphan is a direct arterial vasodilator and an alpha-adrenoceptor antagonist.

作者信息

Harioka T, Hatano Y, Mori K, Toda N

出版信息

Anesth Analg. 1984 Mar;63(3):290-6.

Abstract

In helically cut strips of dog cerebral, mesenteric, and femoral arteries contracted with prostaglandin(PG)F2 alpha, trimethaphan (10(-5)-10(-3)M) caused a dose-related relaxation that was not influenced by atropine, propranolol, diphenhydramine, cimetidine, aminophylline, or indomethacin. Trimethaphan-induced relaxation was greater in extracerebral than in cerebral arteries. The relaxation was greater in phenylephrine-contracted arteries than in PGF2 alpha-contracted arteries. On the other hand, hexamethonium did not relax the arteries. Trimethaphan (10(-4)-10(-3)M) shifted the dose-response curve for norepinephrine in mesenteric arteries to the right, but failed to influence the contractile response to 25 mM KCl. Treatment with trimethaphan (10(-4)-10(-3)M) protected alpha-adrenergic receptors from persistent blockade by phenoxybenzamine. Trimethaphan (10(-7)-3 X 10(-6)M) and hexamethonium (3 X 10(-8)-10(-6)M) significantly attenuated the contractile response of mesenteric arteries to nicotine in a dose-dependent manner, but did not alter the response to transmural electrical stimulation. The antinicotinic potency of trimethaphan was approximately one-fourth that of hexamethonium. It is concluded that, unlike hexamethonium, trimethaphan acts directly on vascular smooth muscle to induce vasodilation, more prominently in extracerebral arteries than in cerebral arteries. In high concentrations, trimethaphan appears to possess an alpha-adrenergic blocking action.

摘要

在与前列腺素（PG）F2α收缩的犬脑动脉、肠系膜动脉和股动脉的螺旋形切片中，三甲噻方（10⁻⁵ - 10⁻³M）引起剂量相关的舒张，该舒张不受阿托品、普萘洛尔、苯海拉明、西咪替丁、氨茶碱或吲哚美辛的影响。三甲噻方诱导的舒张在脑外动脉中比在脑动脉中更大。在去氧肾上腺素收缩的动脉中，舒张比在PGF2α收缩的动脉中更大。另一方面，六甲铵不能使动脉舒张。三甲噻方（10⁻⁴ - 10⁻³M）使肠系膜动脉中去甲肾上腺素的剂量 - 反应曲线右移，但未能影响对25 mM氯化钾的收缩反应。用三甲噻方（10⁻⁴ - 10⁻³M）处理可保护α - 肾上腺素能受体免受苯氧苄胺的持续阻断。三甲噻方（10⁻⁷ - 3×10⁻⁶M）和六甲铵（3×10⁻⁸ - 10⁻⁶M）以剂量依赖的方式显著减弱肠系膜动脉对尼古丁的收缩反应，但不改变对跨壁电刺激的反应。三甲噻方的抗烟碱效力约为六甲铵的四分之一。得出的结论是，与六甲铵不同，三甲噻方直接作用于血管平滑肌以诱导血管舒张，在脑外动脉中比在脑动脉中更显著。在高浓度下，三甲噻方似乎具有α - 肾上腺素能阻断作用。