心肌收缩功能降低对下体负压效应影响的仿真研究

目的：研究不同程度心肌收缩功能降低对心血管系统立位应激反应的影响，探讨心肌收缩功能改变在航天失重心后心血管失调和立位耐力降低机理中的意义。方法：以我们原有仿真血量减少后下体负压（LBNP）暴露时心血管系统反应的模型为基础，对其心脏工作子模型中最大弹性系数（maximum elastance)乘以一个反映心肌收缩功能改变的系数。然后逐渐降低收缩功能改变系，仿真血容量减少12％后，心肌收缩功能降低0－305后LBNP时心率（HR）、血压（BP）和心输出量（CO）的变化。结果：心肌收缩功能降低将使LBNP时，HR加快，BP降低和CO减小。结论：心肌收缩功能降低导致心血管系统对立位应激的调节能力降低。

A Simulation Study of Effects of Depressed Myocardial Contractility on Cardiovascular Response to Lower Body Negative Pressure.

Objective To study the effects of depressed myocardial contra ct ility induced by microgravity on cardiovascular response to orthostatic stress, and to investigate the role played by the changes of myocardial contractility in the mechanism of cardiovascular deconditioning and orthostatic intolerance indu ced by space weightlessness. Method On the basis of our previous mo del used to simulate the cardiovascular response to lower body negative pressure (LBNP),the factor of changes of myocardial contractility was incorporated into the model by multiplying a coefficient to the maximum elastance of the heart wor king sub-model. By decreasing the coefficient progressively,then the changes of heart rate (HR), blood pressure (BP), and cardiac output (CO) during LBNP after 0~30% of myocardial contractility depression combined with 12% decrease of tota l blood volume were simulated. Result Simulation results indicated that depressed myocardial contractility induces more augment of HR, and more dec rease of BP and CO during LBNP. Conclusion The depression of myocar dial contractility degenerated cardiovascular response to orthostatic stress.