The Open UniversitySkip to content
 

Comparison of the T-tubule system in adult rat ventricular and atrial myocytes, and its role in excitation-contraction coupling and inotropic stimulation

Smyrnias, Ioannis; Mair, Waltraud; Harzheim, Dagmar; Walker, Simon A.; Roderick, H. Llewelyn and Bootman, Martin D. (2010). Comparison of the T-tubule system in adult rat ventricular and atrial myocytes, and its role in excitation-contraction coupling and inotropic stimulation. Cell Calcium, 47(3) pp. 210–23.

Warning

This is the latest version of this eprint.

Full text available as:
Full text not publicly available
Due to copyright restrictions, this file is not available for public download
Click here to request a copy from the OU Author.
DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/j.ceca.2009.10.001
Google Scholar: Look up in Google Scholar

Abstract

Narrow, tubular, inward projections of the sarcolemma ('T-tubules') are an established feature of adult mammalian ventricular myocytes that enables them to generate the whole-cell Ca2+ transients and produce coordinated contraction. Loss of T-tubules can occur during ageing and under pathological conditions, leading to altered cardiac excitation-contraction coupling. In contrast to adult ventricular cells, atrial myocytes do not generally express an extensive T-tubule system at any stage of development, and therefore rely on Ca2+ channels around their periphery for the induction of Ca2+ signalling and excitation-contraction coupling. Consequently, the characteristics of systolic Ca2+ signals in adult ventricular and atrial myocytes are temporally and spatially distinct. However, although atrial myocytes do not have the same regularly spaced convoluted T-tubule structures as adult ventricular cells, it has been suggested that a proportion of adult atrial cells have a more rudimentary tubule system. We examined the structure and function of these atrial tubules, and explored their impact on the initiation and recovery of Ca2+ signalling in electrically paced myocytes. The atrial responses were compared to those in adult ventricular cells that had intact T-tubules, or that had been chemically detubulated. We found that tubular structures were present in a significant minority of adult atrial myocytes, and were unlike the T-tubules in adult ventricular cells. In those cells where they were present, the atrial tubules significantly altered the on-set, amplitude, homogeneity and recovery of Ca2+ transients. The properties of adult atrial myocyte Ca2+ signals were different from those in adult ventricular cells, whether intact or detubulated. Excitation-contraction coupling in detubulated adult ventricular myocytes, therefore, does not approximate to atrial signalling, even though Ca2+ signals are initiated in the periphery of the cells in both of these situations. Furthermore, inotropic responses to endothelin-1 were entirely dependent on T-tubules in adult ventricular myocytes, but not in atrial cells. Our data reveal that that the T-tubules in atrial cells impart significant functional properties, but loss of these tubular membranes does not affect Ca2+ signalling as dramatically as detubulation in ventricular myocytes.

Item Type: Journal Article
Copyright Holders: 2010 Elsevier
ISSN: 0143-4160
Academic Unit/Department: Science > Life, Health and Chemical Sciences
Interdisciplinary Research Centre: Biomedical Research Network (BRN)
Item ID: 35104
Depositing User: Martin Bootman
Date Deposited: 20 Nov 2012 11:44
Last Modified: 21 Mar 2014 06:27
URI: http://oro.open.ac.uk/id/eprint/35104
Share this page:

Available Versions of this Item

  • Comparison of the T-tubule system in adult rat ventricular and atrial myocytes, and its role in excitation-contraction coupling and inotropic stimulation. (deposited 20 Nov 2012 11:44) [Currently Displayed]

Altmetrics

Scopus Citations

Actions (login may be required)

View Item
Report issue / request change

Policies | Disclaimer

© The Open University   + 44 (0)870 333 4340   general-enquiries@open.ac.uk