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First published online March 18, 2009

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Seeing cardiomyocyte signalling in 3D

Cardiomyocytes contain defined membranous structures known as dyadic clefts, where short-lived increases in local Ca²⁺ concentration (known as Ca²⁺ sparks) occur; the accumulation of Ca²⁺ sparks following stimulation regulates excitation-contraction (EC) coupling. Microscopy techniques have been useful for understanding the microarchitecture and signalling events in cardiomyocyte membrane systems, although technical limitations have made it difficult to resolve the three-dimensional (3D) structure of dyadic clefts. On p. 1005, Masahiko Hoshijima and colleagues now show that this is possible by using electron tomography to visualise the 3D structure of dyadic clefts across multiple sarcomeres in adult mouse cardiac muscle. In contrast to previous studies, they show that the size of dyadic clefts is highly variable and that many are smaller (<1.5x10⁵ nm³) than previously reported. In addition, observations of Ca²⁺-signalling events lead the authors to speculate that the asymmetrically clustered dyadic clefts defined using electron tomography act as `hot spots' of spontaneous intracellular Ca²⁺ release that stimulate neighbouring Ca²⁺-releasing sites. This work provides insight into the anatomical basis of Ca²⁺-signalling events and EC coupling in cardiomyocytes.

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Takeharu Hayashi, Maryann E. Martone, Zeyun Yu, Andrea Thor, Masahiro Doi, Michael J. Holst, Mark H. Ellisman, and Masahiko Hoshijima
JCS 2009 122: 1005-1013. [Abstract] [Full Text]  

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JCS Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content Social Bookmarking                         What's this?