Nitric oxide synthase-containing neurones and nerve fibres within cardiac ganglia of rat and guinea-pig: an electron-microscopic immunocytochemical study.
The nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity of intracardiac neurones in the rat and guinea-pig was studied at the ultrastructural level. While some nitric oxide synthase-containing intracardiac neurones were very heavily labelled, with electron-dense immunoprecipitate distributed throughout the neuronal cell bodies and their processes, most of the labelled neurones exhibited a lighter and more patchy distribution of nitric oxide synthase-immunoreactive material. Synapses made by nitric oxide synthase-negative nerve fibres with labelled intracardiac neurones were seen. Conversely, many nitric oxide synthase-containing nerve fibres that made synaptic contacts with unlabelled intracardiac neurones were also observed. Some small granule-containing cells were nitric oxide synthase-immunoreactive and were associated with unlabelled nerve terminals, while non-immunoreactive small granule-containing cells that were innervated by nitric oxide synthase-immunoreactive nerves were also seen. Small patches of osmiophilic electron-dense material were observed in the cytoplasm of NADPH-diaphorase-positive intracardiac neurones. This is the first description of the ultrastructural distribution of nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity in a subpopulation of intracardiac neurones of rat and guinea-pig heart and provides further evidence in support of a role for nitric oxide in the local control of the heart by intrinsic neurones.
Sosunov
A A
AA
Department of Anatomy and Developmental Biology and Centre for Neuroscience, University College London, Gower Street, London WC1E 6BT, UK.
Hassall
C J
CJ
Loesch
A
A
Turmaine
M
M
Burnstock
G
G
D000818:Animals; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D005724:Ganglia / Q000201:enzymology; D006168:Guinea Pigs; D006321:Heart / Q000294:innervation; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009412:Nerve Fibers / Q000201:enzymology*; D009474:Neurons / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000032:analysis* / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley
D019001:Nitric Oxide Synthase; D009252:NADPH Dehydrogenase