Nerve injury induces a rapid efflux of nitric oxide (NO) detected with a novel NO microsensor

Shanta M. Kumar, D. Marshall Porterfield, Kenneth J. Muller, Peter J.S. Smith, Christie L. Sahley

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


An early step in repair of the leech CNS is the appearance of endothelial nitric oxide synthase (eNOS) immunoreactivity and NOS activity, but coincident generation of NO at the lesion after injury has not been shown. This is important because NO can regulate microglial cell motility and axon growth. Indirect measurement of NO with the standard citrulline assay demonstrated that NO was generated within 30 min after nerve cord injury. A polarographic NO-selective self-referencing microelectrode that measures NO flux noninvasively was developed to obtain higher spatial and temporal resolution. With this probe, it was possible to demonstrate that immediately after the leech CNS was injured, NO left the lesion with a mean peak efflux of 803 ± 99 fmol NO cm-2 sec-1. NO efflux exponentially declined to a constant value, as described through the equation f(t) = y0 + ae-t/τ, with τ = 117 ± 30 sec. The constant Y0 = 15.8 ± 4.5 fmol cm-2 represents a sustained efflux of NO. Approximately 200 pmol NO cm-2 is produced at the lesion (n = 8). Thus, injury activates eNOS already present in the CNS and precedes the accumulation of microglia at the lesion, consistent with the hypothesis that NO acts to stop the migrating microglia at the lesion site.

Original languageEnglish (US)
Pages (from-to)215-220
Number of pages6
JournalJournal of Neuroscience
Issue number1
StatePublished - Jan 1 2001


  • Endothelial nitric oxide synthase (eNOS)
  • Leech CNS
  • Microglia
  • Nerve injury
  • Nerve repair
  • Nitric oxide (NO)
  • NO efflux
  • NO-selective microsensor
  • Regeneration

ASJC Scopus subject areas

  • Neuroscience(all)


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