Faclors ioncreasing the energy conversion efficiency of myocardial contractile machinery

本项目旨在寻找能够提高心肌收缩机制能量转换效率的因素。我们使用切除的、交叉循环的狗左心室，分析了左心室耗氧量（V02）和收缩压-容积面积（PVA）之间的关系，PVA是衡量心室收缩总机械能的指标。V05-PVA关系的斜率实际上是线性的，它表示收缩机械整体效率的倒数。我们研究了1)在心肌从37℃冷却到29℃的情况下，2)通过降低冠状动脉灌注压从80降至50和30 mmhg的全缺血情况下，以及3)在收缩期间不同释放时间的快速释放收缩。我们发现在冷却和缺血下V02-PVA关系的斜率几乎没有变化。然而，快速释放降低了斜率，表明效率提高。然而，我们将这一结果解释为PVA的维持是能量依赖性的，是维持所节省的V02的缩写。这些结果有助于我们更好地理解心肌力学与能量学之间的耦合关系。

The aim of this project was to search for factors which can increase the energy conversion efficiency of the contractile machinery of myocardium. We used excised, cross-circulated dog left ventricles and analyzed the relationship belween left ventricular oxygen consumption (V02) and systolic pressure-volume area (PVA) as a measure of the total mechanical energy of ventricular contraction. The slope of the V05-PVA relation which is virtually linear indicales the reciprocal of the overall efficiency of the contractile machinery. We studied this efficiency 1) under cooling myocardium from 37C to 29C, 2) under global ischemia by lowering coronary perfusion pressure from 80 to 50 and to 30 mmhg, and 3) in quick release contractions in which release time was varied during systole. We found virtually no change in the slope of the V02-PVA relation under cooling and ischemia. However, quick release decreased the slope, suggesting an increased efficiency. However, We interpreted this result to reflect that the maintenance of PVA is energy-dependent and abbreviation of the maintenance saved V02. All these results help us better understand the coupling between mechanics and energetics of myocardium.