A comparison of cardiovascular and smooth muscle effects of 5-hydroxytryptamine and 5-carboxamidotryptamine, a selective agonist of 5-HT1 receptors.
A comparison of cardiovascular and smooth muscle effects of 5-hydroxytryptamine and 5-carboxamidotryptamine, a selective agonist of 5-HT1 receptors.
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发表时间：
1985-10
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通讯作者：
Saxena Pr;A. Lawang
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作者：
Saxena Pr;A. Lawang
本文比较了5-羟色胺（5-HT）和5-羧酰胺色胺（5-CT）对大鼠心率、动脉血压、膀胱压及豚鼠支气管和回肠的药理作用。5-HT引起短暂的心动过缓和三相血压反应，包括最初的短暂的兴奋，升压，最后，一个较长的持续降压相。与美加明，赛庚啶和酮色林的分析表明，最初的心动过缓和低血压，升压和心动过速反应5-HT是由于，分别是，M和5-HT 2受体。5-CT对这些受体没有或几乎没有活性，但引起明显的肿胀反应。5-HT和5-CT的延长的消肿作用显然是由5-HT 1受体介导的，因为它们不受赛庚啶或酮色林的影响，但被高剂量（大于2.5 mg.kg-1）的麦角新碱拮抗，该麦角新碱对5-HT 1结合位点具有明显的亲和力。对豚鼠支气管和大鼠膀胱，5-HT通过5-HT 2-和膀胱的情况下，也通过M型5-HT受体收缩; 5-CT没有任何影响。低浓度（5 × 10 ~（-6）M）的5-CT使豚鼠离体回肠松弛，可能是通过该组织中的5-HT_1受体，而高浓度的5-CT使回肠收缩。但5-HT通过M-和5-HT_2型5-HT受体对回肠的收缩作用远大于5-CT。我们的研究结果表明，5-CT不仅具有结合，而且对5-HT 1受体的功能特异性。该化合物似乎是研究5-HT 1受体介导的功能反应的有用工具。
The pharmacological effects of 5-hydroxytryptamine (5-HT) on heart rate, arterial blood pressure and urinary bladder pressure in the rat, and on the bronchi and ileum of the guinea-pig were compared with those of 5-carboxamidotryptamine (5-CT), a compound which binds specifically and with high affinity to 5-HT1 binding sites in rat brain membranes. 5-HT caused a transient bradycardia and a triphasic blood pressure response consisting of an initial short-lasting hypotensive, a pressor and, finally, a longer-lasting depressor phase. Analysis with mecamylamine, cyproheptadine and ketanserin indicated that the initial bradycardia and hypotension, and the pressor and tachycardic responses to 5-HT were due to, respectively, the M and 5-HT2 receptors. 5-CT showed no or little activity on these receptors, but elicited a marked hypotensive response. The prolonged hypotensive effects of both 5-HT and 5-CT were apparently mediated by 5-HT1 receptors, since they were unaffected by cyproheptadine or ketanserin, but were antagonized by high doses (greater than 2.5 mg.kg-1) of methysergide, which has an appreciable affinity for 5-HT1 binding sites. On the guinea-pig bronchi and the rat urinary bladder, which were contracted by 5-HT via 5-HT2- and, in the case of bladder, also via M-type 5-HT receptors; 5-CT was without any effect. The guinea-pig isolated ileum was relaxed by low concentration (5 X 10(-6) M), probably via 5-HT1 receptors demonstrated in this tissue, and contracted by higher concentrations of 5-CT. However, the contractile effect of 5-HT on the ileum, exerted via the M- and 5-HT2-type 5-HT receptors, was much more than that of 5-CT. Our results demonstrate that 5-CT not only has a binding, but also a functional specificity for 5-HT1 receptors. This compound seems to be a useful tool for investigating 5-HT1 receptor mediated functional responses.