Comparison of capillary architecture between slow and fast muscles in rats using a confocal laser scanning microscope.
The skeletal muscle is classified into 2 types, slow oxidative or fast glycolytic muscle. For further characterization, we investigated the capillary architecture in slow and fast muscles. The rat soleus and extensor digitorum longus (EDL) muscles were used as representatives of slow and fast muscles, respectively. To investigate capillary density, sections of both types of muscle were stained with alkaline phosphatase; the soleus muscle showed more intense reactivity, indicating that it had a denser capillary structure than the EDL muscle. We then injected fluorescent contrast medium into samples of both muscle types for light and confocal-laser microscopic evaluation. The capillary density and capillary-to-fiber ratio were significantly higher, and the course of the capillaries was more tortuous, in the soleus muscle than in the EDL muscle. Capillary coursed more tortuously in the soleus than in the EDL muscle. Succinate dehydrogenase (SDH) activity, an indicator of mitochondrial oxidative capacity, and vascular endothelial growth factor (VEGF) expression were also significantly higher in the soleus muscle. Thus, we conclude that slow oxidative muscle possess a rich capillary structure to provide demanded oxygen, and VEGF might be involved in the formation and/or maintenance of this highly capillarized architecture.
Murakami
Shinichiro
S
Department of Human Morphology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.
Fujino
Hidemi
H
Takeda
Isao
I
Momota
Ryusuke
R
Kumagishi
Kanae
K
Ohtsuka
Aiji
A
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002196:Capillaries / Q000033:anatomy & histology*; D006019:Glycolysis; D021621:Imaging, Three-Dimensional; D008297:Male; D018613:Microscopy, Confocal; D018656:Muscle Fibers, Fast-Twitch / Q000166:cytology* / Q000378:metabolism; D018657:Muscle Fibers, Slow-Twitch / Q000166:cytology* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000166:cytology / Q000378:metabolism; D009929:Organ Size; D010085:Oxidative Phosphorylation; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013385:Succinate Dehydrogenase / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D013385:Succinate Dehydrogenase; D000469:Alkaline Phosphatase; D010100:Oxygen