Morishita H, Furukawa T
J Pharm Pharmacol. 1975 Aug;27(8):574-9. doi: 10.1111/j.2042-7158.1975.tb09509.x.
The changes elicited after ephedrine tachyphylaxis in the dog femoral and rabbit aortic strips isolated from the untreated and ephedrine pre-treated animals have been studied. In untreated strips, ephedrine exhibited dose-dependent contractions which were blocked by phenoxybenzamine. These contractile responses to ephedrine were reduced after pre-treatment with ephedrine in vivo. In rabbit aortic strips previously contracted with noradrenaline or KCL, ephedrine induced dose-dependent relaxations at high concentrations, which were not affected by propranolol. These relaxation responses were likewise diminished after ephedrine. Dose-related contractile responses to noradrenaline were potentiated at low concentrations and depressed at high concentrations after ephedrine whereas those to adrenaline were inhibited over the entire agonist range. Responses to KCL were not affected. These reductions in the responses to noradrenaline and adrenaline after treatment with ephedrine in vivo were inhibited by icreased calcium2+ concentration. From the results, it can be presumed that the observed changes in vascular responsiveness may be partially involved in the development of ephedrine tachyphylaxis.
对从未经处理和麻黄碱预处理的动物分离出的犬股动脉条和兔主动脉条进行了研究，观察麻黄碱快速耐受性产生后的变化。在未经处理的血管条中，麻黄碱呈剂量依赖性收缩，可被酚苄明阻断。在体内用麻黄碱预处理后，这些对麻黄碱的收缩反应减弱。在预先用去甲肾上腺素或氯化钾收缩的兔主动脉条中，高浓度麻黄碱可诱导剂量依赖性舒张，且不受普萘洛尔影响。这些舒张反应在麻黄碱预处理后同样减弱。麻黄碱处理后，低浓度时对去甲肾上腺素的剂量相关收缩反应增强，高浓度时则减弱，而对肾上腺素的收缩反应在整个激动剂浓度范围内均受到抑制。对氯化钾的反应不受影响。体内用麻黄碱处理后，对去甲肾上腺素和肾上腺素反应的这些减弱可被增加的钙离子浓度抑制。从结果可以推测，观察到的血管反应性变化可能部分参与了麻黄碱快速耐受性的形成。
