Gibbs C L, Wendt I R
J Cardiovasc Pharmacol. 1985 Mar-Apr;7(2):267-72. doi: 10.1097/00005344-198503000-00010.
We studied the effects of amrinone (300 micrograms X ml-1) on the mechanical and energetic outputs of nonfailing rabbit papillary muscles at 27 degrees C using a myothermic technique. Amrinone was found to markedly stimulate the basal (i.e., nonbeating) metabolism. In mechanical experiments, at a 0.5-Hz stimulus rate, amrinone increased the rate of stress development and peak active stress but shortened the time to peak stress and the contractile duration. The linear relationship between total (active + passive) stress and heat production was altered by amrinone such that there was a 68% increase in the activation heat component (intercept) and an 11% increase in the energy cost per unit stress development (slope). In afterloaded isotonic experiments amrinone increased the capacity of papillary muscles to accomplish external work (W) by approximately 50% on average; however, this effect was associated with an increased total energy usage per beat (ET) such that the overall mechanical efficiency (W/ET X 100%) was not significantly altered at any load level. We conclude that amrinone greatly increases calcium delivery to the myofilaments and slightly increases the cost of stress development. These effects are examined in the light of amrinone's postulated mode of action, and possible reasons for the clinical observation of a decrease in myocardial oxygen consumption after amrinone administration are considered.
我们使用肌温测量技术研究了氨力农（300微克×毫升⁻¹）在27℃时对未衰竭兔乳头肌机械和能量输出的影响。发现氨力农能显著刺激基础（即非搏动性）代谢。在机械实验中，以0.5赫兹的刺激频率，氨力农增加了应力发展速率和峰值主动应力，但缩短了达到峰值应力的时间和收缩持续时间。氨力农改变了总（主动+被动）应力与产热之间的线性关系，使得激活热成分（截距）增加了68%，单位应力发展的能量消耗（斜率）增加了11%。在有后负荷的等张实验中，氨力农使乳头肌完成外部功（W）的能力平均提高了约50%；然而，这种效应与每搏总能量消耗（ET）增加有关，以至于在任何负荷水平下整体机械效率（W/ET×100%）均未显著改变。我们得出结论，氨力农大大增加了钙向肌丝的转运，并略微增加了应力发展的成本。根据氨力农假定的作用方式对这些效应进行了研究，并考虑了氨力农给药后心肌氧消耗减少这一临床观察结果的可能原因。
