Nitric oxide synthase in human skeletal muscles related to defined fibre types

Histochem Cell Biol. 2006 May;125(5):567-73. doi: 10.1007/s00418-005-0108-7. Epub 2005 Nov 16.


Skeletal muscle functions regulated by NO are now firmly established. However, the knowledge about the NO synthase (NOS) expression related to a defined fibre type in human skeletal muscles necessitates further clarification. To address this issue, we examined localization of NOS isoforms I, II and III, in human skeletal muscles employing immunocytochemical labeling with tyramide signal amplification complemented with enzyme histochemistry and Western blotting. The NOS immunoreactivity was related to fibre types of different classification systems: physiological classification into slow and fast, ATPase classification into I, IIA, IIAX, IIX, and physiological-metabolic classification into slow-oxidative (SO), fast-oxidative glycolytic (FOG) and fast-glycolytic (FG). We found a correlation of NOS I-III immunoreactivity to metabolic defined fibre types with strong expression in FOG fibres. This implies that NO as modulator of muscle function is involved in oxidative metabolism in connection with fast force development, which only occurs in FOG fibres. The NOS expression showed no correlation to ATPase fibre subtypes due to the metabolic heterogeneity of ATPase fibre types. Healthy and affected vastus medialis muscles after anterior cruciate ligament rupture revealed similar NOS expression level as shown by Western blotting with, however, different expression patterns related to the fibre types in affected muscles. This suggests an altered modulation of force development in the fibres of diseased muscles.

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Adolescent
  • Adult
  • Blotting, Western
  • Female
  • Humans
  • Immunohistochemistry
  • Male
  • Middle Aged
  • Muscle Fibers, Skeletal / enzymology*
  • Muscle, Skeletal / enzymology*
  • Nitric Oxide Synthase / metabolism*
  • Nitric Oxide Synthase Type I / metabolism
  • Nitric Oxide Synthase Type II / metabolism
  • Nitric Oxide Synthase Type III / metabolism


  • NOS1 protein, human
  • NOS2 protein, human
  • NOS3 protein, human
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type I
  • Nitric Oxide Synthase Type II
  • Nitric Oxide Synthase Type III
  • Adenosine Triphosphatases