Three-dimensional distribution of ryanodine receptor clusters in cardiac myocytes

Ye Chen-Izu, Stacey L McCulle, Chris W Ward, Christian Soeller, Bryan M Allen, Cal Rabang, Mark B Cannell, C William Balke, Leighton T Izu

Research output: Contribution to journalArticle (Academic Journal)

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Abstract

The clustering of ryanodine receptors (RyR2) into functional Ca2+ release units is central to current models for cardiac excitation-contraction (E-C) coupling. Using immunolabeling and confocal microscopy, we have analyzed the distribution of RyR2 clusters in rat and ventricular atrial myocytes. The resolution of the three-dimensional structure was improved by a novel transverse sectioning method as well as digital deconvolution. In contrast to earlier reports, the mean RyR2 cluster transverse spacing was measured 1.05 microm in ventricular myocytes and estimated 0.97 microm in atrial myocytes. Intercalated RyR2 clusters were found interspersed between the Z-disks on the cell periphery but absent in the interior, forming double rows flanking the local Z-disks on the surface. The longitudinal spacing between the adjacent rows of RyR2 clusters on the Z-disks was measured to have a mean value of 1.87 microm in ventricular and 1.69 microm in atrial myocytes. The measured RyR2 cluster distribution is compatible with models of Ca2+ wave generation. The size of the typical RyR2 cluster was close to 250 nm, and this suggests that approximately 100 RyR2s might be present in a cluster. The importance of cluster size and three-dimensional spacing for current E-C coupling models is discussed.
Original languageEnglish
Pages (from-to)1-13
Number of pages13
JournalBiophysical Journal
Volume91
Issue number1
Publication statusPublished - 1 Jan 2006

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    Chen-Izu, Y., McCulle, S. L., Ward, C. W., Soeller, C., Allen, B. M., Rabang, C., Cannell, M. B., Balke, C. W., & Izu, L. T. (2006). Three-dimensional distribution of ryanodine receptor clusters in cardiac myocytes. Biophysical Journal, 91(1), 1-13.