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Review article (peer-reviewed)

Journal Biochimica et Biophysica Acta (BBA) - Molecular Cell Research
Volume (Issue) 1867(3)
Page(s) 118502 - 118502
Title of proceedings Biochimica et Biophysica Acta (BBA) - Molecular Cell Research
DOI 10.1016/j.bbamcr.2019.06.016

Open Access

URL https://doi.org/10.1016/j.bbamcr.2019.06.016
Type of Open Access Publisher (Gold Open Access)

Abstract

This work discusses active and passive electrical properties of transverse (T-)tubules in ventricular cardiomyocytes to understand the physiological roles of T-tubules. T-tubules are invaginations of the lateral membrane that provide a large surface for calcium-handling proteins to facilitate sarcomere shortening. Higher heart rates correlate with higher T-tubular densities in mammalian ventricular cardiomyocytes. We assess ion dynamics in T-tubules and the effects of sodium current in T-tubules on the extracellular potential, which leads to a partial reduction of the sodium current in deep segments of a T-tubule. We moreover reflect on the impact of T-tubules on macroscopic conduction velocity, integrating fundamental principles of action potential propagation and conduction. We also theoretically assess how the conduction velocity is affected by different T-tubular sodium current densities. Lastly, we critically assess literature on ion channel expression to determine whether action potentials can be initiated in T-tubules.
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