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JSR and EJSR in the Finch Heart: Morphometry by Serial Sections.

Published online by Cambridge University Press:  02 July 2020

J.R. Sommer ,
T. High ,
R. Nassar  and
I. Taylor
J.R. Sommer
Affiliation:
Dept. of Pathol., Duke Univ., and VA Med. Ctrs., Durham, NC27710
T. High
Affiliation:
Dept. of Pathol., Duke Univ., and VA Med. Ctrs., Durham, NC27710
R. Nassar
Affiliation:
Dept. of Pediatrics, Duke Univ. Med. Ctr., Durham, NC, 27710
I. Taylor
Affiliation:
Dept. of Pathol., Duke Univ., and VA Med. Ctrs., Durham, NC27710
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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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References

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6. Supported by grant NIH HL-12486-27 and VA Research ServiceGoogle Scholar