Ultrastructural localization of nitric oxide synthese immunoreactivity in guinea-pig enteric neurons

Ida J. Llewellyn-Smith, Zan Min Song, Marcello Costa, David S. Bredt, Solomon H. Snyder

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164 Scopus citations


Electron microscopic immunocytochemistry was used to localize immunoreactivity for nitric oxide synthase (NOS) in whole-mount preparations of myenteric plexus and circular muscle from guinea-pig ileum. NOS immunoreactivity was patchily distributed in myenteric neurons and was not specifically associated with any subcellular organelle or with the plasma membrane. This localization leaves unanswered the question of how nitric oxide is stored and released. NOS immunoreactive fibres in the circular muscle were found closer than 100 nm to muscle cells. NOS immunoreactive nerve fibres made synaptic contacts with NOS immunoreactive and non-immunoreactive enteric neurons. These results indicate that nitric oxide may regulate the activity of both myenteric neurons and smooth muscle.

Original languageEnglish (US)
Pages (from-to)337-342
Number of pages6
JournalBrain research
Issue number2
StatePublished - Apr 17 1992


  • Enteric nervous system
  • Immunocytochemistry
  • Nitric oxide synthase
  • Smooth muscle
  • Ultrastructure

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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