Endothelial Type Nitric Oxide Synthase in Skeletal Muscle Fibers: Mitochondrial Relationships

Biochem Biophys Res Commun. 1995 Jun 15;211(2):375-81. doi: 10.1006/bbrc.1995.1824.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Oxidoreductases / analysis
  • Amino Acid Oxidoreductases / metabolism*
  • Animals
  • Arginine / pharmacology
  • Diaphragm
  • Endothelium, Vascular / enzymology
  • Immunohistochemistry / methods
  • Isoenzymes / analysis
  • Isoenzymes / metabolism*
  • Mitochondria, Muscle / drug effects
  • Mitochondria, Muscle / enzymology*
  • Mitochondria, Muscle / metabolism
  • Muscle Fibers, Skeletal / enzymology*
  • Muscle, Skeletal / enzymology*
  • Nitric Oxide Synthase
  • Organ Specificity
  • Oxygen Consumption / drug effects
  • Rats
  • Stereoisomerism


  • Isoenzymes
  • Arginine
  • Nitric Oxide Synthase
  • Amino Acid Oxidoreductases