Capillary electrophoresis analysis of nitric oxide synthase related metabolites in single identified neurons

Anal Chem. 1998 Jun 1;70(11):2243-7. doi: 10.1021/ac9713013.


Intracellular concentrations of L-citrulline (Cit) and its metabolites are related to nitric oxide synthase (NOS) activity, an enzyme producing the intercellular messenger NO in animal tissues including the nervous system. A capillary electrophoresis system using laser-induced fluorescence detection is described, and methods are developed to monitor the levels of L-arginine (Arg), Cit, and related molecules in identified neurons of the marine slugs, Pleurobranchaea californica and Aplysia californica. The limits of detection for Arg, Cit, L-arginino-succinate, L-ornithine, and L-arginine phosphate range from 50 amol to 17 fmol (5 nM to 17 microM in the neurons under study); these detection limits are significantly lower than actual intracellular levels of the metabolites, allowing the direct assay of single cells. The levels of NOS metabolites in individual neurons varied form 6 (Arg) and 4 mM (Cit) in putative NOS-containing neurons down to < 1 microM (undetectable) levels in many putative NOS-negative cells. The Arg/Cit ratio is independent of cell volume, correlates with NADPH-diaphorase staining, and appears to be a characteristic parameter for the presence of NOS activity in identified neurons.

Publication types

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

MeSH terms

  • Animals
  • Aplysia
  • Arginine / analogs & derivatives
  • Arginine / analysis*
  • Argininosuccinic Acid / analysis
  • Citrulline / analysis*
  • Electrophoresis, Capillary
  • Mollusca
  • Nerve Tissue Proteins / metabolism*
  • Neurons / metabolism*
  • Nitric Oxide Synthase / metabolism*
  • Nitric Oxide Synthase Type I
  • Organophosphorus Compounds / analysis
  • Ornithine / analysis


  • Nerve Tissue Proteins
  • Organophosphorus Compounds
  • phospho-L-arginine
  • Argininosuccinic Acid
  • Citrulline
  • Arginine
  • Ornithine
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type I