模拟失重对心肌超微结构与氧供需能力的影响

为探讨失重条件下心肌超微结构变化的性质与心肌的氧供需平衡状况，观察了尾部悬吊８周大鼠心肌超微结构，定性观察发现，与对照组相比，悬吊组大鼠左室心肌细胞中溶酶体与脂褐素的数量明显增多。发生退行性变化的线性体数量增加。未见线粒体空泡化嵴断裂，肿胀等现象，心肌细胞肌浆网囊泡不仅明显缩小，且横切面上的肌浆网囊泡数量也明显减少；心肌毛细血管内皮细胞伸向管腔的突起多用延长，定量观察发现，悬吊组心肌肌原纤维的体密

Effects of Simulated Weightlessness on Ultrastructures and Oxygen Supply and Consumption of Myocardium in Rats.

Weightlessness causes atrophy of myocardium in rats,however,properties of ultrastructural changes and oxygen supply and consumption in myocardiun are still unclear.Changes in ultrastructures of left ventricular myocardium in rats tail-suspended for 8W were observed.Qualitative analysis showed that the lysosomes, lipofuscins and degenerate mitochondria increased in myocytes of left ventricle in tail-suspended rats (SUS). The sarcoplasmic reticula were reduced in quantity and shrunken in appearance. The number of extended endothelial projections into the lumen of capillaries increased. Quantitative analysis showed that volume densities of mitochondria and sarcoplasmic reticulum in SUS were reduced by 14.5% and 22.2%,respectively.The number density of mitochondria also had a 12.5% decrease in SUS. The morphometric data-estimated oxygen demand of the myocardium in SUS showed a 16.7% decrease.These results suggested that the feature of the changes be chronic degeneration without the evidence of acute hypoxia in myocardium.The decrease of oxygen consumption of myocardium in SUS didn't cause a reflex reduction in the oxygen supply.