Sheard, TMD orcid.org/0000-0003-4940-3188, Kharche, SR, Pinali, C et al. (1 more author) (2019) 3D ultrastructural organisation of calcium release units in the avian sarcoplasmic reticulum. Journal of Experimental Biology, 222 (7). jeb.197640. ISSN 0022-0949
Abstract
Excitation-contraction coupling in vertebrate hearts is underpinned by calcium (Ca2+) release from Ca2+ release units (CRUs). CRUs are formed by clusters of channels called ryanodine receptors on the sarcoplasmic reticulum (SR) within the cardiomyocyte. Distances between CRUs influence the diffusion of Ca2+, thus influencing the rate and strength of excitation-contraction coupling. Avian myocytes lack T-tubules, thus Ca2+ from surface CRUs (peripheral couplings, PCs), must diffuse to internal CRU sites of the corbular SR (cSR) during centripetal propagation. Despite this, avian hearts achieve higher contractile rates and develop greater contractile strength than many mammalian hearts, which have T-tubules to provide simultaneous activation of the Ca2+ signal through the myocyte. We used 3D electron tomography to test the hypothesis that the intracellular distribution of CRUs in the avian heart permits faster and stronger contractions despite the absence T-tubules. Nearest edge-edge distances between PCs and cSR, and geometric information including surface area and volumes of individual cSR, were obtained for each cardiac chamber of the White Leghorn chicken. Computational modelling was then used to establish a relationship between CRUs distances and cell activation time in the avian heart. Our data suggest that cSR clustered close together along the Z-line is vital for rapid propagation of the Ca2+ signal from the cell periphery to the cell centre which would aid in the strong and fast contractions of the avian heart.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © 2019. Published by The Company of Biologists Ltd. This is an author produced version of a paper published in Journal of Experimental Biology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Bird; Chicken; Computational model; Calcium diffusion; Electron tomography; Peripheral coupling |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 01 Mar 2019 10:24 |
Last Modified: | 27 Feb 2020 01:38 |
Status: | Published |
Publisher: | Company of Biologists |
Identification Number: | 10.1242/jeb.197640 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:143084 |