Hashimoto H, Nakashima M
Eur J Pharmacol. 1978 Aug 15;50(4):337-47. doi: 10.1016/0014-2999(78)90139-5.
Effects of thyroxine treatment for 7--11 days on the positive inotropic effects mediated by alpha- and beta-adrenoceptors were studied in isolated guinea pig atria and rabbit papillary muscles. In guinea pig atria, the thyroxine treatment inhibited the positive inotropic effect of lower concentrations of phenylephrine (PHE), and attenuated the inhibitory effect of phentolamine on the PHE response. The effect of isoproterenol (ISO) was potentiated by the thyroxine treatment. In rabbit papillary muscles, the thyroxine treatment shifted the dose--response curve for PHE to the right and attenuated the inhibitory effect of phentolamine on the PHE response. Propranolol, in both guinea pig atria and rabbit papillary muscles, inhibited the PHE response more effectively in preparations from thyroxine-treated animals than in controls. In guinea peg atria, the attenuation of the PHE response mediated by alpha-adrenoceptors was observed after the thyroxine treatment for only 2 days, whereas the potentiation of the ISO response required the thyroxine treatment for a longer period. It was concluded that the thyroxine treatment attenuated the positive inotropic effect mediated by alpha-adrenoceptors and potentiated that mediated by beta-adrenoceptor-mediated positive inotropic effects due to the thyroxine treatment may be independent of each other.
在离体豚鼠心房和兔乳头肌中研究了甲状腺素治疗7 - 11天对α和β肾上腺素能受体介导的正性肌力作用的影响。在豚鼠心房中，甲状腺素治疗抑制了较低浓度去氧肾上腺素（PHE）的正性肌力作用，并减弱了酚妥拉明对PHE反应的抑制作用。甲状腺素治疗增强了异丙肾上腺素（ISO）的作用。在兔乳头肌中，甲状腺素治疗使PHE的剂量 - 反应曲线右移，并减弱了酚妥拉明对PHE反应的抑制作用。在豚鼠心房和兔乳头肌中，普萘洛尔在甲状腺素治疗动物的标本中比在对照中更有效地抑制PHE反应。在豚鼠心房中，甲状腺素治疗仅2天后就观察到α肾上腺素能受体介导的PHE反应减弱，而ISO反应的增强需要更长时间的甲状腺素治疗。得出的结论是，甲状腺素治疗减弱了α肾上腺素能受体介导的正性肌力作用，并增强了β肾上腺素能受体介导的正性肌力作用，甲状腺素治疗引起的这两种作用可能相互独立。
