[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.


CONCLUSIONS
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.
Huang
Q
Q
Department of Pathophysiology and Institute of High Altitude Medicine, The Third Military Medical University, Chongqing 400038, China.
Gao
Y
Y
Shi
J
J
Liu
F
F
Cao
L
L
Sun
B
B
D000818:Animals; D002196:Capillaries / Q000473:pathology; D005260:Female; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology; D018919:Neovascularization, Physiologic; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2