模拟失重大鼠不同部位动脉血管壁超微结构的变化

目的研究模拟失重下身体不同部位动脉血管壁结构重塑变化的性质及其可逆性。方法用透射电镜观察尾部悬吊４ｗｋ（ＳＵＳ４）、悬吊４ｗｋ后恢复１ｗｋ（ＲＥＣ１）、及对照（ＣＯＮ）大鼠后肢和头颈部动脉血管壁的超微结构改变。结果后肢的动脉血管（如股动脉及胫前动脉）的改变是：ＳＵＳ４组平滑肌层数减少、平滑肌细胞内肌丝减少，间质胶原增多；ＲＥＣ１组内弹力层增厚，平滑肌细胞内肌丝增加，内皮下出现合成表型的新生平滑肌细胞，间质量减少；头颈部的动脉血管（如颈总动脉及基底动脉）的变化：平滑肌细胞层数增加，细胞增生，由收缩表型向合成表型转化，以及平滑肌细胞迁移等；ＲＥＣ１组上述改变有部分恢复。结论对飞行后立位耐力降低的外周效应器机制假说提出了新的实验证据。

Ultrastructural Changes of Arterial Wall from Different Body Parts of Rats during Simulated Weightlessness

Objective To test the nature of remodeling of arteries in different body parts in adapting to local hemodynamic changes induced by tail suspension. Method Ultrastructural changes of hindlimb and cerebral arteries from 4 wk tail suspended (SUS 4),1 wk recovered (REC 1),and control (CON) rats were studied by transmission electron microscopy.Result For the hindquarter arteries,like the femoral artery and anterior tibial artery,there were fewer smooth muscle layers ,less myofilaments in the smooth muscle cell (SMC),and more intercellular substance in SUS 4 group than in CON group.After 1 wk recovery,the internal elastic lamina of the arteries thickened,the amount of myofilaments in SMC increased,the content of intercellular substance restored,and neoformative SMCs emerged under the endothelium. With respect to arteries in the neck region and the brain,like the common carotid artery and basilar artery,SMCs of contractile phenotype were converted to that of synthetic phenotype,and migration and hyperplasia of SMCs also happened.After 1 wk recovery all these alterations were somewhat restored. Conclusion It provided further evidence that peripheral effector mechanism might play an important role in the genesis of postflight orthostatic intolerance.