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Distribution and morphology of sensory and autonomic fibres in the subendocardial plexus of the rat heart

Shenton, F.C.; Campbell, T.; Jones, J.F.X.; Pyner, S.

Distribution and morphology of sensory and autonomic fibres in the subendocardial plexus of the rat heart Thumbnail


Authors

F.C. Shenton

T. Campbell

J.F.X. Jones



Abstract

Cardiac reflexes originating from sensory receptors in the heart ensure blood supply to vital tissues and organs in the face of constantly changing demands. Atrial volume receptors are mechanically sensitive vagal afferents which relay to the medulla and hypothalamus, affecting vasopressin release and renal sympathetic activity. To date, two anatomically distinct sensory endings have been identified which may subserve cardiac mechanosensation: end‐nets and flower‐spray endings. To map the distribution of atrial receptors in the subendocardial space, we have double‐labelled rat right atrial whole mounts for neurofilament heavy chain (NFH) and synaptic vesicle protein 2 (SV2) and generated high‐resolution maps of the rat subendocardial neural plexus at the cavo‐atrial region. In order to elucidate the nature of these fibres, double labelling with synaptophysin (SYN) and either NFH, calcitonin gene‐related peptide (CGRP), choline acetyltransferase (ChAT) or tyrosine hydroxylase (TH) was performed. The findings show that subendocardial nerve nets are denser at the superior cavo‐atrial junction than the mid‐atrial region. Adluminal plexuses had the finest diameters and stained positively for synaptic vesicles (SV2 and SYN), CGRP and TH. These plexuses may represent sympathetic post‐ganglionic fibres and/or sensory afferents. The latter are candidate substrates for type B volume receptors which are excited by stretch during atrial filling. Deeper nerve fibres appeared coarser and may be cholinergic (positive staining for ChAT). Flower‐spray endings were never observed using immunohistochemistry but were delineated clearly with the intravital stain methylene blue. We suggest that differing nerve fibre structures form the basis by which atrial deformation and hence atrial filling is reflected to the brain.

Citation

Shenton, F., Campbell, T., Jones, J., & Pyner, S. (2020). Distribution and morphology of sensory and autonomic fibres in the subendocardial plexus of the rat heart. Journal of Anatomy, 238(1), 36-52. https://doi.org/10.1111/joa.13284

Journal Article Type Article
Acceptance Date Jul 2, 2020
Online Publication Date Aug 11, 2020
Publication Date 2020
Deposit Date Aug 4, 2020
Publicly Available Date Aug 18, 2020
Journal Journal of Anatomy
Print ISSN 0021-8782
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 238
Issue 1
Pages 36-52
DOI https://doi.org/10.1111/joa.13284
Public URL https://durham-repository.worktribe.com/output/1264664

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Advance online version © 2020 The Authors. Journal of Anatomy published by John Wiley & Sons Ltd on behalf of Anatomical Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.






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