Van der Graaf P H, Shankley N P, Black J W
Leiden/Amsterdam Center for Drug Research, Division of Pharmacology, Sylvius-Laboratories, The Netherlands.
Naunyn Schmiedebergs Arch Pharmacol. 1996 Aug-Sep;354(3):389-92. doi: 10.1007/BF00171074.
We have studied the effects of idazoxan in rat aorta and small mesenteric artery. In the aorta, idazoxan behaved as a partial agonist (pKA = 6.30). Prazosin produced rightward shift (pA2 = 9.88) and steepening of the idazoxan curve. In contrast, idazoxan had no effect of basal tension in the mesenteric artery, but shifted the noradrenaline curve to the right in a parallel manner (pA2 = 6.12). The selective alpha 1-adrenoceptor agonist, indanidine, also behaved as a partial agonist in the aorta and produced no significant contractions of the small mesenteric artery. Since idazoxan and indanidine have been reported to raise blood pressure in the pithed rat via an action at vascular alpha 1-adrenoceptors, these results call into question the reliability of the small mesenteric artery assay as a predictor for alpha 1-adrenoceptor-mediated pressor activity in vivo.
我们研究了吲哚哌唑对大鼠主动脉和小肠系膜动脉的作用。在主动脉中，吲哚哌唑表现为部分激动剂（pKA = 6.30）。哌唑嗪使吲哚哌唑曲线右移（pA2 = 9.88）并使其变陡。相比之下，吲哚哌唑对肠系膜动脉的基础张力无影响，但使去甲肾上腺素曲线平行右移（pA2 = 6.12）。选择性α1 -肾上腺素能受体激动剂茚达立啶在主动脉中也表现为部分激动剂，对小肠系膜动脉无明显收缩作用。由于据报道吲哚哌唑和茚达立啶通过作用于血管α1 -肾上腺素能受体使脊髓麻醉大鼠血压升高，这些结果质疑了小肠系膜动脉试验作为体内α1 -肾上腺素能受体介导的升压活性预测指标的可靠性。
