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Roles of baroreflex in controlling energy efficiency of ventricular arterial coupling

压力反射在控制心室动脉耦合能量效率中的作用

基本信息

批准号：
03670458
负责人：
SUNAGAWA Kenji
金额：
$ 1.28万
依托单位：
National Cardiovascular Center Research Institute (1992)Kyushu University (1991)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03670458/
关键词：
cardiac efficiency baroreflex end-systolic elastance effective arterial elastance transfer function 収縮効率

项目摘要

The heart contracts incessantly over the life time. The average number of contraction for men exceeds 2.5 billion times. Since each ejection requires large amount of energy, the total amount of energy expenditure by the heart becomes enormous. Thus it is conceivable that, in response to changes in demands for the heart, the regulatory system adjusts ventricular contraction so that energy efficiency of the heart becomes maximal.To test this hypothesis, in chronically instrumented dogs, we measured efficiency of ventricular contraction during exercise. The results indicated that the oxygen consumption of the left ventricle was nearly minimum at rest for a given amount of cardiac work. At the same time, external work of the left heart was maximal for a given preload. These optimal conditions were hardly affected by exercise.To further investigate what regulatory mechanisms are responsible for this optimization, we evaluated the roles of baroreflex. In acute open-chest dogs, we isolated th … More e carotid sinuses and altered intrasinus pressure. We measured left ventricular end-systolic elastance and effective arterial elastance beat-by-beat. The effect of the baroreflex on these elastances were quantitated using transfer functions in the frequency domain. The transfer functions from intrasinus pressure to end-systolic elastance and to effective arterial elastance resembled each other. They showed characteristics of the second order delay system. The gains in the low frequency range were similar. The corner frequencies were around 0.03 Hz and were not significantly different. Since efficiency of ventricular ejection was a function of the ratio of end-systolic elastance to effective arterial elastance, these findings suggested the ratio may well be maintained during the entire time course of baroreflex. This is to say that the optimal condition was maintained when the baroreflex system stabilizes arterial pressure. Whether this optimization is truly nature's goal when ventricular arterial coupling is regulated remains to be investigated. Less

心脏在一生中不断地收缩。男性平均宫缩次数超过25亿次。由于每次射血都需要大量的能量，心脏消耗的能量总量变得巨大。因此，可以想象，在响应心脏的需求的变化，调节系统调整心室收缩，使心脏的能量效率变得最大。为了验证这一假设，在长期仪表狗，我们测量了心室收缩效率在运动过程中。结果表明，对于一定的心脏作功量，静息时左心室耗氧量接近最低。同时，对于给定的前负荷，左心的外功最大。为了进一步研究压力感受性反射的调节机制，我们评估了压力感受性反射的作用。在急性开胸犬中，我们分离了 ...更多信息 e颈动脉窦和窦内压改变。我们逐搏测量左心室收缩末期弹性和有效动脉弹性。压力反射对这些弹性的影响在频域中使用传递函数进行定量。窦内压向收缩末期弹性和有效动脉弹性的传递函数相似。它们表现出二阶时滞系统的特征。低频范围内的增益相似。转角频率约为0.03 Hz，没有显著差异。由于心室射血效率是收缩末期弹性与有效动脉弹性之比的函数，因此这些发现表明，在压力感受性反射的整个时间过程中，该比率可以很好地维持。也就是说，当压力反射系统稳定动脉压时，维持最佳状态。这种优化是否是真正的性质的目标时，心室动脉耦合的调节仍有待研究。少