[Echocardiographic assessment of left ventricular structure and function after simulated weightlessness in rats]

Objective. To investigate whether the changes in rat after simulated weightlessness are similar to those in astronaut after flight. Methods. The effects of 4 wk tail-suspension on left ventricular structure and function in rats were examined by echocardiography. Results. After 4 wk of simulated weightlessness, the thickness of both the anterior and posterior wall in left ventricle (LV) showed a general trend of decrease, but these changes were not statistically significant; the end-systolic and end-diastolic internal dimensions (ESD and EDD respectively) of LV decreased significantly; and the end-systolic volume, end-diastolic volume and stroke volume (ESV, EDV and SV respectively) were all reduced; so did the relevant indices of them. There were no significant differences in ejection fraction (EF) and fractional shortening (FS) between the tail-suspended and control groups. The left ventricular mass (LVM) and its index (LVMI) were decreased. The peak velocities of blood flow of aorta, pulmonary artery and mitral valve didn't show any significant change after simulated weightlessness. Conclusion. Medium-term simulated weightlessness may lead to a significant decrease in left ventricular internal dimension, ventricular volume, and mass, and a trend of decrease in mean left ventricular wall thickness. These changes in rats are similar to those observed in astronauts postflight.