尾部悬吊大鼠胸主动脉、肺动脉超微结构变化的动态观察

The dynamic observation of ultrastructual changes of the walls in aortae and pulmonary arteries from the rats under tail suspension

目的观察模拟微重力时大小循环动脉血管超微结构重塑随时间变化的差异,为微重力后立位耐力降低的机制研究积累资料。方法用透射电镜观察-30°尾部悬吊7d(TS7组)、14d(TS14组)及对照组大鼠胸主动脉、肺动脉壁超微结构的变化。结果TS7组胸主动脉内皮细胞表面出现绒毛状突起,部分线粒体空泡变性,内皮下基膜有分层,内弹力板较厚,且厚度不均匀,内弹力板下出现大量的胶原纤维;TS14组胸主动脉内皮细胞变性较明显,部分内皮细胞基质致密化,基膜复层化,内弹力板有破碎,弹力纤维增多。TS7组肺动脉部分内皮细胞突起,细胞内出现脂滴,内皮细胞基膜出现分层状改变,弹力板变薄、断裂,其下方可见收缩型平滑肌及合成型平滑肌细胞;TS14组肺动脉内皮细胞空泡变性较明显,内弹力板未见明显改变,弹力板内外均可见较多的胶原纤维和弹力纤维,内弹力板下方以收缩型平滑肌为主。结论TS7组大鼠胸主动脉和肺动脉出现损伤和增殖并存,以肺动脉较明显;TS14组肺动脉趋于形成新的稳定结构,而胸主动脉新稳定结构还未形成。模拟微重力时大小循环血管发生了结构重塑,大小循环血管重塑的时间过程不同归因于模拟微重力初期由下体转移而来的体液进入大小循环高峰期的时间差。

Objective To investigate various effects of simulated microgravity on systematic circulation and pulmonary circulation for the mechanism researches of orthostatic intolerance after microgravity. Methods Ultrastructure changes of thoracic aortae and pulmonary arteries from 7 and 14 days -30° tail suspension （TST, TSI4 ） and control rats were observed by transmission electron microscopy. Results Electron micrographey of thoracic aortae from TS7 rats showed some floss tubers on the surface of endothelial cells, vacuole denaturalization of mitochodria in endothelial cells, some delaminated basic membrane under endothelial cells, thicker and more asymmetry internal elastic lamina , a mass of collagen and contractile phenotype smooth muscle cells under internal elastic lamina. Those from TS14 rats appeared multistratum of basic membrane, denser cytoplasm, more obvious denaturalization in the endothelial cells, the fragmentation of the internal elastic lamina and more elastin under internal elastic lamina. Those of pulmonary arteries from TS7 rats showed some tubers on the surface of endothelial cells, some lipid drops in the endothelial cells, the stratification in basic membrane of the endothelial cells, synthetic and contractile phenotype smooth muscle cells under the thinner and chapped internal elastic lamina. Those of pulmonary arteries from TS14 rats showed vacuole denaturalization of the endothelial cells, more elastin and collagen under and above internal elastic lamina, and mainly contractile phenotype smooth muscle cells under internal elastic lamina. Conclusions Artery walls of TS7 rats show some structural damage accompanied with some proliferation of cells, which is more obvious in pulmonary arteries compared to aortae. The walls of pulmonary arteries of TS14 rats become stable, but those of aortae remain unstable. Some arterial structural remodeling occurs and presents some differences between systematic and pulmonary blood vessels under simulated microgravity, which may be due to the difference in the peak course of the shift of fluid from lower body entering into pulmonary and systematic circulation during initial simulated microgravity.