目的验证模拟失重４ｗｋ大鼠心脏左室的结构与功能是否出现类似航天员飞行后的变化。方法应用超声心动图技术检测模拟失重大鼠心脏左室的结构与功能。结果模拟失重４ｗｋ大鼠左室舒张末与收缩末短径均显著减小；左室壁厚度亦减小，但差别未达显著程度。左室舒张末与收缩末容积、每搏量及其相应的体重归一化指数皆显著减少，左室估计质量及其指数亦显著减少。但左室射血分数与短轴收缩率，主动脉瓣、肺动脉瓣及二尖瓣处多普勒峰值血流速度则皆无显著改变。结论４ｗｋ模拟失重大鼠左室的超声心动图表现类似航天员飞行后的变化。其主要改变为：左室心腔短径变短，左室壁厚度呈减小趋势，左室估计容积与质量皆显著减少，但一些心肌收缩功能指标却未见有明显变化。 Objective To verify whether the structure and function of the left ventricle of a simulated 4 wk rat is similar to that of astronauts after the flight. Methods The structure and function of left ventricle in simulated weightless rats were detected by echocardiography. Results After 4 wk of simulated weightlessness, the left ventricular end-diastolic dimension and the shortened end-systolic diameter were all significantly decreased. The left ventricular wall thickness also decreased, but the difference was not significant. Left ventricular end-diastolic volume and end-systolic volume, stroke volume and corresponding weight normalization index were significantly reduced, LV mass and its index were also significantly reduced. However, left ventricular ejection fraction and short axis contraction rate, aortic valve, pulmonary valve and mitral valve Doppler peak blood flow velocity were not significantly changed. Conclusions Left ventricular echocardiography in 4 wk simulated weightless rats showed similar changes after astronaut flight. The main changes are: left ventricular short axis becomes shorter, left ventricular wall thickness decreased, left ventricular estimated volume and quality were significantly reduced, but some myocardial systolic function index but no significant change.