Ishisu R, Abe Y, Onishi K, Ueda Y, Sekioka K, Nakano T
First Department of Internal Medicine, Mie University School of Medicine, Tsu, Japan.
J Pharmacol Toxicol Methods. 1996 Feb;35(1):55-61. doi: 10.1016/1056-8719(95)00113-1.
To elucidate the issues such as excitation-contraction coupling and myocardial ischemia, it is necessary to measure intracellular free Ca2+ concentration and mechanical function of hearts perfused via the normal arterial circulation. For this purpose, we simultaneously measured Ca(2+)-dependent indo-1 fluorescence and left ventricular (LV) pressure on a beat-to-beat basis in Langendorff guinea-pig hearts, and investigated the changes in Ca2+ transient and LV function during inotropic stimulation and myocardial ischemia. The indo-1 fluoresence ratio and LV developed pressure increased the perfusate [Ca2+] increased from 1.6 to 3.2 mmol/L, and there was a good correlation between Ca2+ transient and LV contractility. Digoxin (10(-6) mol/L) and milrinone (10(-5) mol/L) increased LV contractility with a concomitant increase in Ca2+ transient, and the relative increase of Ca2+ transient produced by milrinone was much more than that by digoxin. The reduction of coronary perfusion pressure from 80 to 40 mm Hg decreased LV contractility with an increase in indo-1 fluorescence ratio. These results suggest that Ca2+ responsiveness of contractile apparatus declines during inotropic stimulation by milrinone and during myocardial ischemia. Thus, this experimental technique is useful to investigate the interrelation of Ca2- regulation and LV function during a variety of pharmacological and physiologic perturbations.
为了阐明诸如兴奋 - 收缩偶联和心肌缺血等问题，有必要测量经正常动脉循环灌注的心脏的细胞内游离钙离子浓度和机械功能。为此，我们在Langendorff豚鼠心脏上逐搏同时测量了钙离子依赖性吲哚 - 1荧光和左心室（LV）压力，并研究了变力刺激和心肌缺血期间钙离子瞬变和左心室功能的变化。当灌注液中钙离子浓度从1.6 mmol/L增加到3.2 mmol/L时，吲哚 - 1荧光比率和左心室舒张末期压力增加，并且钙离子瞬变和左心室收缩性之间存在良好的相关性。地高辛（10^(-6) mol/L）和米力农（10^(-5) mol/L）增加左心室收缩性，同时钙离子瞬变增加，并且米力农产生的钙离子瞬变的相对增加远大于地高辛。冠状动脉灌注压力从80 mmHg降低到40 mmHg会降低左心室收缩性，同时吲哚 - 1荧光比率增加。这些结果表明，在米力农的变力刺激期间和心肌缺血期间，收缩装置的钙离子反应性下降。因此，这种实验技术对于研究各种药理和生理扰动期间钙离子调节与左心室功能之间的相互关系是有用的。
