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JSR and EJSR in the Finch Heart: Morphometry by Serial Sections.
Published online by Cambridge University Press: 02 July 2020
Extract
“Coupling(s)” (Fig. 1) are structure complexes in cardiac muscle consisting of junctional SR (JSR) tightly apposed to the cytoplasmic side of the plasmalemma. They are either peripheral (PC; when on the cell surface) or interior (IC; when on transverse tubule(s), TT). The JSR is a store for calcium (Ca)-release through Ca channels/ryanodine receptors in junctional processe(s) (JP) on the JSR surfaces. Action potential(s) (AP) for excitation-contraction coupling translate, as mediated by L-type channels, into Ca-entry into a ˜ 20 nm junctional gap (JG) containing JP between plasmalemma and the JSR's junctional membrane proper. In mammalian cardiac myocyte(s) (CM), where IC are ubiquitously distributed along TT at Z-bands, an AP quickly effects almost simultaneous global contraction, even in the center of cells of large diameter, whence CICR can be viewed as a one-step event between Ca-entry and JSR Ca-release from couplings. Avian CM, however, have no TT and, thus, only PC.
- Type
- Imaging Cells and Organelles
- Information
- Microscopy and Microanalysis , Volume 3 , Issue S2: Proceedings: Microscopy & Microanalysis '97, Microscopy Society of America 55th Annual Meeting, Microbeam Analysis Society 31st Annual Meeting, Histochemical Society 48th Annual Meeting, Cleveland, Ohio, August 10-14, 1997 , August 1997 , pp. 249 - 250
- Copyright
- Copyright © Microscopy Society of America 1997
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