摘要
心脏收缩释放的能量(作功)是心肌纤维长度(心室舒张末期容积,EDV)的函数,即Frank-Star-ling(FS)心脏作功定律,被誉为心脏生理学中的"经典"理论。对此,笔者从各种不同角度进行了探讨:首先分析了Frank伸展离体心肌和Starling及其同事使用心肺制备做的实验与动物生理实际的差异,以及人们在实验中观测到的增加心肌前负荷引起收缩力增强的现象(FS现象),认为:①在正常生理条件下的动物体内,来自心脏以外的、如同心肺制备中那样人工控制心室充盈压力升高、引起EDV增加的那种血液的重力动力是不存在的。②另一方面,人为地增加前负荷,那是改变了心肌收缩时的外环境条件。③由此而激发出的FS现象,是心脏适应其外环境条件变化所作出的反应。④此种心肌收缩力增强的反应,需通过心肌细胞内部与收缩过程发生有关的心肌兴奋-收缩和化学-力学偶联等一系列生化机制(不恒定因素)方能得以实现。⑤根据他们实验中观测到的FS现象,在逻辑上不能得出前负荷这一心肌收缩时的外环境条件变化调控其作功的推论。换言之,所有的在实验中被激发出来的FS现象,都不足以成为支持FS心脏定律的证据。然后,引用国内外公认的计算心脏每搏射血作功(W)的生物物理学公式"W=P×(EDV-ESV)",证明了W和EDV之间没有函数关系。根据心脏作功的医用物理学和生物数学的基本原理,笔者认为Frank-Starling心脏定律表达的不是心脏作功的规律。
The theory that the energy of cardiac contraction （cardiac work） is a function of the length of the muscle fiber （the end-diastolic volume,EDV） has been known as the Frank-Starling law of the heart （FS- LH ）, which is reputed as the ＂classic mechanism＂ in physiology of the heart. The FSLH is discussed from va- rious perspectives in this paper. First of all, this paper analyzed the difference between both of Frank＇s experi- ments of the stretch of isolated cardiac muscle and Starling＇s heart-lung preparation and the animal physiologi- cal practice, and focused on the Frank-Starling phenomenon [FSP） in the experiments, in which the increase in the preloads of the cardiac muscle enhances the contractility. The paper concludes that： （ 1 ） under normal physiological condition, from the outside of the heart, there is no such power that the potential energy of the venous blood was controlled in Starling and his associates＇ experiments, in which the artificial increase in the filling pressure caused the increase in the EDV; （2） the artificial increase of the preloads in the experiments, as far as the work of cardiac muscle contraction concerned, can certainly change the external environmental condition during contraction; （3 ） the FSP shown/provoked in the experiments is a response to adapt to the changes in the external environmental condition during contraction; （4） the response of the increase in the con- tractility to the increase of the preload has to undergo a train of mechanisms of excitation-contraction and chemical-mechanic coupling （changing factors） within myocardial cells; （5） therefore on the basis of the FSP in the experiments, people have concluded that the preload （one of the external environmental condition during contraction） may regulate and determine the cardiac work, which does not logically agree with the basics of scientific epistemology, viz. all the FSPs observed in the experiments do not provide enough evidence to sup- port the FSLH. Then, the authors quote the biophysical formula of cardiac work ＂Strokework = P ~ （EDV -- ESV）＂ which has been universally adopted to prove that there is no functional relation between the cardiac work and the EDV. According to the heart workings basic principle of biomathcmatsics and medical physics, the authors hold that the FSLH is a failure as a law to express the heart working.
出处
《西部医学》
2009年第10期1639-1646,共8页
Medical Journal of West China
