Lefebvre R A
Heymans Institute of Pharmacology, University of Gent Medical School, Belgium.
J Pharm Pharmacol. 1992 Apr;44(4):330-6. doi: 10.1111/j.2042-7158.1992.tb03616.x.
The inhibitory effect of dopamine has been studied in longitudinal and circular muscle strips of the cat gastric fundus. When tone was raised by transmural electrical stimulation and by administration of methacholine, dopamine concentration-dependently relaxed the strips but the inhibitory effect of dopamine was clearly more pronounced on electrically-induced tone. The effect of dopamine was not influenced by the presence of cocaine or hydrocortisone. The relaxant effect of dopamine, when tone was raised by methacholine, was not influenced by alpha- and dopamine receptor antagonists but it was significantly reduced by propranolol and ICI 118551 (erythro-DL-1-(7-methylindan-4-yloxy)-3- isopropylaminobutan-2-ol). The inhibitory effect of dopamine on the electrically-induced tone was significantly reduced by phentolamine; domperidone tended to reduce the effect of the lower concentrations of dopamine. In the presence of propranolol, phentolamine and rauwolscine concentration-dependently antagonized the inhibitory effect of dopamine on electrically-induced tone, while prazosin was without influence. These results indicate that the inhibitory effect of dopamine in the cat gastric fundus is mainly due to interaction with postjunctional beta 2-adrenoceptors on the smooth muscle cells and with prejunctional alpha 2-adrenoceptors on the intramural cholinergic neurons.
已在猫胃底的纵行肌条和环行肌条中研究了多巴胺的抑制作用。当通过经壁电刺激和给予乙酰甲胆碱使肌张力升高时，多巴胺浓度依赖性地使肌条松弛，但多巴胺对电诱导肌张力的抑制作用明显更显著。多巴胺的作用不受可卡因或氢化可的松存在的影响。当通过乙酰甲胆碱使肌张力升高时，多巴胺的松弛作用不受α受体和多巴胺受体拮抗剂的影响，但普萘洛尔和ICI 118551（erythro-DL-1-(7-甲基茚满-4-基氧基)-3-异丙氨基丁-2-醇）可使其显著降低。酚妥拉明可显著降低多巴胺对电诱导肌张力的抑制作用；多潘立酮倾向于降低较低浓度多巴胺的作用。在普萘洛尔存在的情况下，酚妥拉明和萝芙木碱浓度依赖性地拮抗多巴胺对电诱导肌张力的抑制作用，而哌唑嗪则无影响。这些结果表明，多巴胺在猫胃底的抑制作用主要是由于与平滑肌细胞上的节后β2肾上腺素能受体以及壁内胆碱能神经元上的节前α2肾上腺素能受体相互作用所致。
