Shepperson N B, Duval N, Langer S Z
Eur J Pharmacol. 1982 Jul 30;81(4):627-35. doi: 10.1016/0014-2999(82)90352-1.
The decrease in mesenteric blood flow produced by dopamine administered intra-arterially in the anaesthetised dog was investigated by means of drugs selective for alpha 1- and alpha 2-adrenoceptors. The selective alpha 1-adrenoceptor agonist phenylephrine (0.3-100 microgram) given by intra-arterial injection (i.a.) into the superior mesenteric artery of the anaesthetized dog produced a decrease in mesenteric blood flow which was preferentially blocked by the alpha 1-adrenoceptor antagonist prazosin (30-300 microgram/kg i.v.). On the other hand, i.a. injections of the selective alpha 2-adrenoceptor agonist M7 (1-100 microgram) or of dopamine (1-300 microgram) produced a decrease in mesenteric blood flow which was blocked by the alpha 2-adrenoceptor antagonist yohimbine (100-300 microgram/kg i.v.) but was not significantly reduced by prazosin (300 microgram/kg i.v.). These results demonstrate that the mesenteric vascular bed of the dog contains both alpha 1- and alpha 2-adrenoceptors located postsynaptically and mediating vasoconstriction. The decrease in mesenteric blood flow produced by i.a. injections of dopamine is mediated predominantly via postsynaptic alpha 2-adrenoceptors.
通过对α1和α2肾上腺素能受体有选择性的药物，研究了麻醉犬动脉内注射多巴胺所引起的肠系膜血流量减少情况。给麻醉犬的肠系膜上动脉动脉内注射（i.a.）选择性α1肾上腺素能受体激动剂去氧肾上腺素（0.3 - 100微克），可使肠系膜血流量减少，而α1肾上腺素能受体拮抗剂哌唑嗪（30 - 300微克/千克静脉注射）能优先阻断这种减少。另一方面，动脉内注射选择性α2肾上腺素能受体激动剂M7（1 - 100微克）或多巴胺（1 - 300微克）可使肠系膜血流量减少，这种减少可被α2肾上腺素能受体拮抗剂育亨宾（100 - 300微克/千克静脉注射）阻断，但哌唑嗪（300微克/千克静脉注射）不能使其显著降低。这些结果表明，犬的肠系膜血管床含有位于突触后、介导血管收缩的α1和α2肾上腺素能受体。动脉内注射多巴胺所引起的肠系膜血流量减少主要通过突触后α2肾上腺素能受体介导。
