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...
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Published in | The Journal of physiology Vol. 508; no. 1; pp. 145 - 152 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
The Physiological Society
01.04.1998
Blackwell Science Ltd Blackwell Science Inc |
Subjects | |
Online Access | Get full text |
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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. |
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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 |