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Localization of nitric oxide synthase in human skeletal muscle

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The present study investigated the cellular localization of the neuronal type I and endothelial type III nitric oxide synthase in human skeletal muscle. Type I NO synthase immunoreactivity was found in the sarcolemma and the cytoplasm of all muscle fibres. Stronger immunoreactivity was expressed in the sarcolemma as well as the cytoplasm of type I muscle fibres. NADPH diaphorase activity confirmed a higher level of NO synthase activity in the sarcolemma as well as the cytoplasm of type I muscle fibers. Histochemical staining for cytochrome oxidase showed a staining pattern similar to that observed for type I NO synthase immunoreactivity and NADPH diaphorase activity. Type III NO synthase immunoreactivity was observed both in the endothelium of larger vessels and of microvessels. The results establish that human skeletal muscle expresses two different constitutive isoforms of NO synthase in different cellular compartments and suggest that NO may have specific actions in relation to its site of production. The localization of type I NO synthase in the vicinity of mitochondria supports a specific action of NO on mitochondrial respiration, whereas the localization of type III NO synthase in vascular endothelium is consistent with a role for NO in the control of blood flow in human skeletal muscle.
OriginalsprogEngelsk
TidsskriftBiochemical and Biophysical Research Communications
Vol/bind227
Udgave nummer1
Sider (fra-til)88-93
Antal sider6
ISSN0006-291X
DOI
StatusUdgivet - 1996

Bibliografisk note

PUF "Før 1998" 5200 028

ID: 18695014