title: Origin of neuronal nitric oxide synthase (NOS)-immunoreactive fibers in guinea pig parasympathetic cardiac ganglia.
abstract: This study was conducted to determine the origin(s) of neuronal nitric oxide synthase-immunoreactive (NOS-IR) fibers within guinea pig atrial whole-mount preparations containing the cardiac ganglia. Intrinsic NOS-IR cardiac neurons exhibited choline acetyltransferase (ChAT) immunoreactivity, indicating that they were cholinergic as well as nitrergic. Comparison of control versus 72-hour explant culture preparations indicated that most of the nitrergic fibers within cardiac ganglia were extrinsic. The extrinsic NOS-IR fibers were not IR for ChAT (marker of preganglionic parasympathetic neurons), tyrosine hydroxylase (marker of catecholaminergic sympathetic postganglionic axons), or calcitonin gene-related peptide (CGRP) (marker of afferent fibers). Separate NOS-IR and ChAT-IR neurons were present within medullary regions containing the cardiovascular regulatory nuclei (nucleus ambiguus and dorsal motor nucleus of the vagus), but no cells were found that exhibited both NOS immunoreactivity and ChAT immunoreactivity. The small size and location of the medullary NOS-IR neurons suggested they were probably interneurons. Only an occasional sympathetic postganglionic cell in the stellate ganglion complex exhibited NOS immunoreactivity. NOS-IR cells were present in dorsal root ganglia (thoracic 1-5), but these typically also exhibited CGRP immunoreactivity. NOS-IR cells were also present in the nodose ganglia, but only some exhibited CGRP immunoreactivity. We concluded that virtually all the extrinsic NOS-IR nerve fibers represented an afferent fiber input that was separate from the substance P (SP)/CGRP-containing population of sensory fibers. Furthermore, much of this NOS innervation is probably derived from the nodose ganglia.
authors.affiliation: Department of Anatomy and Neurobiology, College of Medicine, University of Vermont, Burlington, Vermont 05405, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Calupca
authors.forename: M A
authors.initials: MA
authors.lastname: Vizzard
authors.forename: R L
authors.initials: RL
authors.lastname: Parsons
mesh_terms: D000344:Afferent Pathways / Q000201:enzymology; D000818:Animals; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D005260:Female; D005726:Ganglia, Parasympathetic / Q000166:cytology / Q000201:enzymology* / Q000502:physiology; D005727:Ganglia, Spinal / Q000166:cytology / Q000201:enzymology / Q000502:physiology; D005728:Ganglia, Sympathetic / Q000166:cytology / Q000201:enzymology / Q000502:physiology; D006168:Guinea Pigs / Q000378:metabolism*; D006329:Heart Conduction System / Q000166:cytology / Q000201:enzymology* / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D008526:Medulla Oblongata / Q000201:enzymology*; D009412:Nerve Fibers / Q000378:metabolism*; D009474:Neurons / Q000201:enzymology; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D012016:Reference Values; D009435:Synaptic Transmission / Q000502:physiology; D014018:Tissue Distribution; D014630:Vagus Nerve / Q000166:cytology / Q000201:enzymology / Q000502:physiology
chemical_list: D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D002795:Choline O-Acetyltransferase