Eijgelshoven M H, Hak J B, Van Beek J H, Westerhof N
Laboratory for Physiology, Free University, Amsterdam, The Netherlands.
Am J Physiol. 1993 Dec;265(6 Pt 2):H1893-8. doi: 10.1152/ajpheart.1993.265.6.H1893.
The purpose of the present study was to determine whether the mean response time of cardiac mitochondrial oxygen consumption after a step in metabolic demand is constant in heart muscle, as has already been found for skeletal muscle. The mean response time reflects the average delay between the change in ATP hydrolysis due to a heart rate step and mitochondrial ATP production. Isolated rabbit hearts with a water-filled balloon in the left ventricle were perfused according to Langendorff with a constant flow of Tyrode solution at 28 degrees C. The mean response time increased significantly from 7.6 s for a step in heart rate from 60 to 70 min-1 to 12.1 s for a step from 60 to 120 min-1. The mean response times for heart rate steps downward from 120 min-1 were all approximately 12 s, but for the step from 120 to 140 min-1 the response time was 16.8 s. These results demonstrate that the mean response time of cardiac mitochondrial oxygen consumption in most cases increases with heart rate. These findings are in contrast to those obtained in skeletal muscle, where the response time at which ATP synthesis adapts to a change in work load is constant.
本研究的目的是确定心肌中代谢需求发生阶跃后，心脏线粒体耗氧量的平均反应时间是否像在骨骼肌中已发现的那样保持恒定。平均反应时间反映了由于心率阶跃导致的ATP水解变化与线粒体ATP产生之间的平均延迟。将左心室内装有水囊的离体兔心按照Langendorff法在28℃下用恒流的台氏液灌注。平均反应时间从心率从60次/分钟升至70次/分钟时的7.6秒显著增加到从60次/分钟升至120次/分钟时的12.1秒。心率从120次/分钟向下阶跃时的平均反应时间均约为12秒，但从120次/分钟升至140次/分钟时的反应时间为16.8秒。这些结果表明，在大多数情况下，心脏线粒体耗氧量的平均反应时间随心率增加。这些发现与在骨骼肌中获得的结果形成对比，在骨骼肌中，ATP合成适应工作负荷变化的反应时间是恒定的。
