Endothelial type nitric oxide synthase in skeletal muscle fibers: mitochondrial relationships.
Immunohistochemistry shows that skeletal muscle fibers express endothelial-type (ec)-NOS in a heterogeneous pattern distinct from that of neuronal (nc)-NOS. Analysis of adjacent serial sections reveals: 1) a strong correlation of ec-NOS expression to mitochondrial content (visualized histochemically by succinate dehydrogenase); 2) lack of correlation of ec-NOS to fiber ATPase type (in contrast to nc-NOS); and 3) constitutive co-expression of ec- and nc-NOS in some fibers. Preparations of mitochondria from diaphragm exhibited calcium-dependent NOS activity, which functioned to inhibit in vitro oxygen consumption. The results establish that normal skeletal muscle cells can express two constitutive isoforms of NOS (nc- and ec-) and suggest a functional role for ec-NOS in oxidative, mitochondria-rich fibers.
Kobzik
L
L
Physiology Program, Harvard School of Public Health, Boston, MA 02115.
Stringer
B
B
Balligand
J L
JL
Reid
M B
MB
Stamler
J S
JS
D000594:Amino Acid Oxidoreductases / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D003964:Diaphragm; D004730:Endothelium, Vascular / Q000201:enzymology; D007150:Immunohistochemistry / Q000379:methods; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism*; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000201:enzymology*; D018482:Muscle, Skeletal / Q000201:enzymology*; D019001:Nitric Oxide Synthase; D009928:Organ Specificity; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D013237:Stereoisomerism
D007527:Isoenzymes; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases