Intrasarcomere [Ca2+] gradients and their spatio-temporal relation to Ca2+ sparks in rat cardiomyocytes

Line-scan analyses of spontaneous Ca 2+ sparks, non-propagating local rises in Ca 2+ concentration, and the early phase of Ca 2+ transients in cardiomyocytes were performed with a rapid-scanning laser confocal microscope (Nikon RCM8000) and fluo-3. On electrical stimulation, points at which rise in...

Full description

Saved in:
Bibliographic Details
Published inThe Journal of physiology Vol. 508; no. 1; pp. 145 - 152
Main Authors Tanaka, Hikaru, Sekine, Toshiyuki, Kawanishi, Toru, Nakamura, Ryu, Shigenobu, Koki
Format Journal Article
LanguageEnglish
Published Oxford, UK The Physiological Society 01.04.1998
Blackwell Science Ltd
Blackwell Science Inc
Subjects
Online AccessGet full text

Cover

Loading…
More Information
Summary:Line-scan analyses of spontaneous Ca 2+ sparks, non-propagating local rises in Ca 2+ concentration, and the early phase of Ca 2+ transients in cardiomyocytes were performed with a rapid-scanning laser confocal microscope (Nikon RCM8000) and fluo-3. On electrical stimulation, points at which rise in Ca 2+ began earliest were observed at regular spacings of 1.82 ± 0.26 μm (mean ± s.d.) along the longitudinal axis of the cell. The points were heavily stained with di-2-ANEPEQ, which stains the T-tubules, indicating that they were at the Z-line. The points where spontaneous Ca 2+ sparks originated coincided with the points which showed faster Ca 2+ elevation, i.e. the Z-line. In some cases where a Ca 2+ spark had occurred within about 30 ms before the evoked Ca 2+ transient, fast elevation of Ca 2+ was not observed at the corresponding Z-line, indicating the presence of a refractory period in Ca 2+ release from the SR. The present results provide visual evidence for Ca 2+ release from the junctional sarcoplasmic reticulum in cardiomyocytes. The presence of a refractory period in Ca 2+ release after Ca 2+ sparks provided new evidence that the normal Ca 2+ transient may be the summation of Ca 2+ sparks.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:0022-3751
1469-7793
DOI:10.1111/j.1469-7793.1998.145br.x