目的探讨模拟失重是否可引起后肢肌肉小动脉网各级血管内径发生改变及其可逆性。方法采用墨汁灌注法观察尾部悬吊４ｗｋ（ＳＵＳ４），悬吊４ｗｋ后恢复１ｗｋ（ＲＥＣ１）、恢复５ｗｋ（ＲＥＣ５），以及对照（ＣＯＮ）大鼠比目鱼肌小动脉网各级血管内径的变化。结果在ＳＵＳ４组，比目鱼肌的营养动脉、弓状小动脉及Ｖ、Ｉ级横行小动脉的内径，较ＣＯＮ组分别减小了３１％、２９％、２８％及４１％（均为Ｐ＜０．０１）；在ＲＥＣ１组，仅有部分恢复但仍普遍低于ＣＯＮ组（Ｐ＜０．０５，Ｐ＜０．０１）；在ＲＥＣ５组，除Ｉ级横行小动脉外，其余各级小动脉的内径均已恢复。结论４ｗｋ模拟失重大鼠后肢肌肉小动脉可能发生萎缩性变化。本工作还提示小动脉网的结构变化可能是飞行后引起立位耐力降低的重要发生原因之一 Objective To investigate whether simulated weight loss can cause vascular medial diameter changes at all levels of hindlimb arteriolar network and its reversibility. Methods The tail suspension 4wk (SUS4), the recovery 1wk (REC1) and the recovery 5wk (REC5) after 4wk suspension were observed by ink perfusion method, and the contralateral (CON) rat soleus arteriolar network Vascular diameter changes. Results The diameters of nutrient arteries, arcuate arterioles and V- and I-grade transverse arterioles in SUS4 group and soleus muscle decreased by 31%, 29%, 28% and 41% respectively compared with those in CON group <0.01). In the REC-1 group, only part of the recovery was still lower than that in the CON group (P <0.05, P <0.01). In the REC-5 group, , The rest of the arterial diameter at all levels have been restored. Conclusion Atrophic changes of hindlimb arterioles may occur in 4 wk simulated weightless rats. This work also suggests that changes in the structure of the arteriolar network may be one of the important causes of post-flight reduced endurance