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Journal of Biomedicine and Biotechnology
Volume 2011, Article ID 382586, 14 pages
Research Article

Dynamic Changes in Sarcoplasmic Reticulum Structure in Ventricular Myocytes

Department of Physiology & Biophysics, University of Washington, Box 357290, Seattle, WA 98195, USA

Received 29 April 2011; Accepted 9 August 2011

Academic Editor: Xupei Huang

Copyright © 2011 Amanda L. Vega et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The fidelity of excitation-contraction (EC) coupling in ventricular myocytes is remarkable, with each action potential evoking a [ C a 2 + ] 𝑖 transient. The prevalent model is that the consistency in EC coupling in ventricular myocytes is due to the formation of fixed, tight junctions between the sarcoplasmic reticulum (SR) and the sarcolemma where C a 2 + release is activated. Here, we tested the hypothesis that the SR is a structurally inert organelle in ventricular myocytes. Our data suggest that rather than being static, the SR undergoes frequent dynamic structural changes. SR boutons expressing functional ryanodine receptors moved throughout the cell, approaching or moving away from the sarcolemma of ventricular myocytes. These changes in SR structure occurred in the absence of changes in [ C a 2 + ] 𝑖 during EC coupling. Microtubules and the molecular motors dynein and kinesin 1(Kif5b) were important regulators of SR motility. These findings support a model in which the SR is a motile organelle capable of molecular motor protein-driven structural changes.