Martinez E, Fuentes T, Collado M C, Hernández J
Departmento de Farmacologia, Facultad de Medicina, Murcia, Spain.
Res Commun Mol Pathol Pharmacol. 1997 May;96(2):157-67.
The effects of isoprenaline and forskolin were studied on contractile response and cyclic AMP levels in the right ventricle strips of the rat heart. Isoprenaline, in concentrations ranging from 10 nM to 1 microM, significantly increased, in a concentration-dependent manner, the contractile force in this preparation. Forskolin (1-10 microM), which directly stimulates adenylate cyclase, also produced a concentration-dependent increase in cardiac contractility. The mean EC50 (microM) for the contractile action of isoprenaline was 0.08 +/- 0.014 and that of forskolin 7.3 +/- 1.1 being about 70 times less potent than isoprenaline. However, isoprenaline (0.1 microM) and forskolin (8 microM), which produced about the same inotropic response, increased tissue cyclic AMP levels by about two and five fold respectively, when compared to the basal value. These figures further indicate that while the intracellular levels of cyclic AMP in rat ventricular myocardium may be an important determinant of positive inotropism, the connection between the two parameters is more complex than the simple ratio between the tension generated and the amount of cyclic AMP found inside the cells.
研究了异丙肾上腺素和福斯高林对大鼠心脏右心室条带收缩反应和环磷酸腺苷（cAMP）水平的影响。浓度范围为10 nM至1 μM的异丙肾上腺素以浓度依赖性方式显著增加了该制剂中的收缩力。直接刺激腺苷酸环化酶的福斯高林（1 - 10 μM）也使心脏收缩力呈浓度依赖性增加。异丙肾上腺素收缩作用的平均半数有效浓度（EC50，μM）为0.08 ± 0.014，福斯高林的为7.3 ± 1.1，其效力约为异丙肾上腺素的70分之一。然而，产生大致相同变力性反应的异丙肾上腺素（0.1 μM）和福斯高林（8 μM），与基础值相比，分别使组织cAMP水平增加了约两倍和五倍。这些数据进一步表明，虽然大鼠心室心肌中cAMP的细胞内水平可能是正性肌力作用的重要决定因素，但这两个参数之间的联系比细胞内产生的张力与cAMP量之间的简单比例更为复杂。
