Regulation of the rate of synthesis of nitric oxide by MG2+ and hypoxia. Studies in rat heart mitochondria

S. Manzo-Ávalos, V. Pérez-Vázquez, J. Ramírez, L. Aguilera-Aguirre, J. C. González-Hernández, M. Clemente-Guerrero, R. Villalobos-Molina, A. Saavedra-Molina

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23 Scopus citations


In isolated rat heart mitochondria, L-arginine is oxidized by a nitric oxide synthase (mtNOS) achieving maximal rates at 1mM L-arginine. The NOS inhibitor NG-nitro-L-arginine methyl ester (NAME) inhibits the increase in NO production. Extramitochondrial free magnesium inhibited NOS production by 59% at 3.2mM. The mitochondrial free Mg2+ concentration increased to different extents in the presence of L-arginine (29%), the NO donor (S-nitroso-N-acetylpenicillamine) (105%) or the NOS inhibitors L-NAME (48%) or NG-nitro-L-arginine methyl ester, NG-monomethyl-L-arginine (L-NMMA) (53%). Under hypoxic conditions, mtNOS activity was inhibited by Mg2+ by up to 50% after 30 min of incubation. Reoxygenation restored the activity of the mtNOS to pre-hypoxia levels. The results suggest that in heart mitochondria there is an interaction between Mg2+ levels and mtNOS activity which in turn is modified by hypoxia and reoxygenation.

Original languageEnglish (US)
Pages (from-to)381-389
Number of pages9
JournalAmino Acids
Issue number4
StatePublished - 2002
Externally publishedYes


  • Amino acids
  • Free magnesium
  • Heart mitochondria
  • Hypoxiareoxygenation
  • L-Arginine
  • Nitric oxide

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Organic Chemistry


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