Mugelli A, Ledda F, Mantelli L, Torrini M, Maccioni T
Naunyn Schmiedebergs Arch Pharmacol. 1977 Dec;301(1):49-55. doi: 10.1007/BF00501263.
The positive inotropic effect of dopamine has been studied in isolated ventricular strips of guinea-pig heart. The concentration-inotropic response curve for dopamine was significantly shifted to the right by pretreatment with reserpine. In preparations obtained from animals pretreated with reserpine (2.5 mg/kg, 24 h prior to the experiment) the dose-response curve was not significantly affected by haloperidol, a dopamine vascular receptor antagonist (10(-6)-3X10(-6) M). The inotropic effect of dopamine was antagonized by practolol (3X10(-7)-10(-6) M), but not by phentolamine (3X10(-6)-10(-5) M); moreover the alpha-adrenoceptor blocking drug (10(-5) M) did not affect the curve for dopamine in the presence of practolol (3X10(-7) M). In preparations in which fast sodium channels were blocked by K+ -rich medium, slow electrical responses (calcium-mediated action potentials) as well as contractions were induced by high concentrations of dopamine (10(-4)-3X10(-4) M); again these responses were unaffected by phentolamine or haloperidol, but were blocked by practolol. It was concluded that in the guinea-pig ventricular muscle dopamine induced a positive inotropic effect through both indirect and direct action, and that the latter is due to the activation of beta-adrenoceptors.
已在豚鼠心脏离体心室肌条上研究了多巴胺的正性肌力作用。利血平预处理使多巴胺的浓度 - 肌力反应曲线显著右移。在用利血平（2.5mg/kg，实验前24小时）预处理的动物所制备的标本中，多巴胺血管受体拮抗剂氟哌啶醇（10(-6)-3×10(-6)M）对剂量 - 反应曲线无显著影响。多巴胺的正性肌力作用被心得宁（3×10(-7)-10(-6)M）拮抗，但未被酚妥拉明（3×10(-6)-10(-5)M）拮抗；此外，在存在心得宁（3×10(-7)M）的情况下，α - 肾上腺素能受体阻断药（10(-5)M）不影响多巴胺的曲线。在高钾培养基阻断快速钠通道的标本中，高浓度多巴胺（10(-4)-3×10(-4)M）可诱导缓慢电反应（钙介导的动作电位）以及收缩；同样，这些反应不受酚妥拉明或氟哌啶醇影响，但被心得宁阻断。得出的结论是，在豚鼠心室肌中，多巴胺通过间接和直接作用诱导正性肌力作用，且后者是由于β - 肾上腺素能受体的激活。
