Nitric oxide synthase-containing neurones and nerve fibres within cardiac ganglia of rat and guinea-pig: an electron-microscopic immunocytochemical study

• Published in: Cell and tissue research Vol. 284; no. 1; p. 19
• Main Authors: Sosunov, A A, Hassall, C J, Loesch, A, Turmaine, M, Burnstock, G
• Format: Journal Article
• Language: English
• Published: Germany 01.04.1996
• Subjects: Animals; Cytoplasmic Granules - ultrastructure; Ganglia - enzymology; Guinea Pigs; Heart - innervation; Immunohistochemistry - methods; Male; NADPH Dehydrogenase - metabolism; Nerve Fibers - enzymology; Neurons - enzymology; Nitric Oxide Synthase - analysis; Nitric Oxide Synthase - immunology; Rats; Rats, Sprague-Dawley
• ISSN: 0302-766X
• DOI: 10.1007/s004410050563

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.