长期尾部悬吊大鼠冠脉血流量的变化

采用放射性生物微球技术观察了经受４０和１２０ｄ尾部悬吊模拟失重大鼠冠脉血流量及冠脉阻力的变化。４０及１２０ｄ悬吊大鼠冠脉血流量分别较其相应对照组减少２５％（Ｐ＜０．０１）和２２％（Ｐ＜０．０５）；而４０ｄ组和１２０ｄ组的冠脉阻力与其相应配对对照组相比分别升高３７％（Ｐ＜０．０５）和３１％（Ｐ＜０．０５）。此外，悬吊４０ｄ与悬吊１２０ｄ组大鼠左心室重量分别较其配对的对照组大鼠要减轻９％（Ｐ＜０．０５）及５％（Ｐ＜０．０１）。结果表明，长期模拟失重大鼠心脏可能处于低动力状态，从而使心肌的代谢活动减弱并可能发生萎缩。

CORONARY BLOOD FLOW AFTER LONG-TERM TAIL-SUSPENSION IN RATS

The aim of this study was to investigate whether the enhanced ultrastructural degradation changes found previously in the myocardium of the tail-suspended rats were accompanied by an alteration in the coronary blood flow. Male Sprague-Dawley rats were either subjected to a modified tail-suspension for 40 days (n=10) or 120 days (n=9) or served as pair-fed controls.The coronary blood flow of the entire left ventricle was determined in anesthetized rats by left atrial injection of the biologic microspheres prepared by labeling the red cells of toads with NaCrO4 and then fixing it in 1% glutaraldehyde. Following 40-day or 120-day tail-suspension, the left ventricular weight was decreased by 9%(P<0.05) or 5% (P<0.01) respectively as compared with the pair-fed control animals, implicating the occurrence of the myocardial atrophy. The coronary blood flow of the entire left ventricle was decreased by 25% (P<0.01) or 22%(P<0.05), while the coronary resistance increased by 37% (P<0.05) or 31% (P<0.05) in 40-day or 120-day tail-suspended rats respectively as compared with the values of control rats.The results are in accordance with the previously observed morphologic changes and indicate an attenuated myocardial metabolic activity in hypodynamic state of the heart during the long-term simulated weightlessness.