Faclors ioncreasing the energy conversion efficiency of myocardial contractile machinery

本课题的目的是寻找提高心肌收缩机制能量转换效率的因素。本文采用离体犬左心室，分析了左心室氧耗量（V02）与收缩压-容积面积（PVA）的关系。V05-PVA关系的斜率实际上是线性的，表明收缩机构的总效率的倒数。我们研究了这种效率：1）在将心肌从37 ℃冷却到29 ℃的情况下，2）在通过将冠状动脉灌注压从80降至50和30 mmHg的全脑缺血情况下，3）在收缩期间释放时间不同的快速释放收缩中。我们发现在冷却和局部缺血下，V02-PVA关系的斜率几乎没有变化。然而，快速释放降低了斜率，表明效率增加。然而，我们解释了这个结果，以反映PVA的维持是能量依赖的，并且维持的缩短节省了V02。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。

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.