缺氧及缺氧复合运动大鼠骨骼肌毛细血管密度的变化及机制

目的 观察缺氧及在缺氧条件下运动对大鼠骨骼肌毛细血管密度和血管内皮细胞生长因子（ＶＥＧＦ）及其受本ＫＤＲ的影响。方法 用肌球蛋白ＡＴＰ酶组织化学法对大鼠腓肠肌毛细血管和Ⅰ、Ⅱ型肌纤维染色并进行图像分析;用免疫组织化学ＳＰ法对骨骼肌组织中ＶＥＧＦ和ＫＤＲ进行染色。结果 单纯慢性所氧动物骨骼肌纤维萎缩,毛细血管密度显著增加,毛细血管／肌纤维（Ｃ／Ｆ）的比值无明显变化;动物在缺氧条件下运动５周（１ｈ／ｄ,６ｄ／周）后,骨骼肌纤维不发生萎缩,毛细血管密度增加,Ｃ／Ｆ明显升高。免疫组织化学染色发现,ＶＥＧＦ主要分布于组织间隙中,在微血管周围较为明显;单纯缺氧大鼠骨骼肌ＶＥＧＦ无明显变化,而在缺氧条件下复合运动时,骨骼肌组织中ＶＥＧＦ明显增加。ＫＤＲ主要分布于骨骼肌毛细血管的内皮细胞,各组间ＫＤＲ未见明显差异。结论 单纯缺

Effects of hypoxia alone or exercise combined on capillarization of rat gastrocnemius muscle and its mechanism

OBJECTIVE: To study the effects of hypoxia and hypoxia-combined-exercise on capillary density and vascular endothelial growth factor (VEGF) and its receptor KDR of skeletal muscle in rats. METHODS: Myosin-ATPase histochemistry was used to assay the size and capillary density of skeletal muscle. VEGF and its receptor KDR were studied by immunohistochemistry. RESULTS: Five-week hypoxia (simulated 5,000 m altitude) resulted in a decrease in cross-sectional area of skeletal muscle fiber and an increase in capillary density (CD), but the capillary/fiber ratio (C/F) remained unchanged. After 5-week-exercise at high altitude (1 h/d, 6 d/w), the muscle fibers did not undergo atrophy. At the same time, CD and C/F were increased. VEGF protein was found primarily in the matrix between muscle fibers; VEGF receptor-KDR was shown mainly in endothelial cells of capillary. VEGF was more strongly stained in the skeletal muscle of hypoxia-combined-exercise rats than the other two groups. CONCLUSION: Hypoxia itself can not induce neovascularization, while hypoxia-combined-exercise rats show capillary proliferation in skeletal muscle. VEGF and its receptor might play roles in this process.