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

Autor: James F. X. Jones, Susan Pyner, Fiona C. Shenton, Thomas Campbell
Rok vydání: 2020
Předmět:
0301 basic medicine
Histology
Sensory Receptor Cells
Tyrosine 3-Monooxygenase
calcitonin gene‐related peptide
Calcitonin Gene-Related Peptide
synaptophysin
Calcitonin gene-related peptide
neurofilament
Autonomic Nervous System
Synaptic vesicle
end‐net
Choline O-Acetyltransferase
03 medical and health sciences
0302 clinical medicine
Nerve Fibers
tyrosine hydroxylase
Animals
plasma volume regulation
Molecular Biology
atrial mechanoreceptors
Ecology
Evolution
Behavior and Systematics
Medulla
mechanotransduction
biology
Chemistry
synaptic vesicle protein 2
Heart
Cell Biology
Anatomy
Choline acetyltransferase
Immunohistochemistry
Original Papers
choline acetyltransferase
Atrial volume receptors
Rats
flower‐spray endings
030104 developmental biology
Hypothalamus
Synaptophysin
biology.protein
Cholinergic
methylene blue
Original Article
atrial volume receptors
complex unencapsulated endings
030217 neurology & neurosurgery
Developmental Biology
Zdroj: Journal of Anatomy
Journal of anatomy, 2020, Vol.238(1), pp.36-52 [Peer Reviewed Journal]
ISSN: 1469-7580
Popis: 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.
In search of atrial volume receptors, we performed immunohistochemical characterisation of the subendocardial nerve plexus of the rat right atrium. Rats possess a bicuspid Eustachian valve which is richly innervated. Fine adluminal end‐nets expressed vesicular markers, CGRP and tyrosine hydroxylase. Immunohistochemistry did not label flower‐spray endings but these were identified with methylene blue. The observed plexuses could represent sympathetic post‐ganglionic and/or sensory afferents.
Databáze: OpenAIRE
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