Abstract
Since increased muscle activity, which results in fast-slow fiber transformation, is associated with increases in sarcoplasmic Ca2+ concentration ([Ca2+](i)), it seemed of interest to study the level of [Ca2+] after cessation of stimulation in fibers of the extensor digitorum longus muscle chronically stimulated (8 Hz). [Ca2+](i) was measured in individual fibers with a Ca2+-sensitive electrode after subtracting the membrane potential, measured simultaneously from the potential of the Ca2+ electrode. During the first 14 days of stimulation, [Ca2+](i) increased from ~0.1 to 0.5 μM and declined in ~3 wk to a value slightly higher than the initial one. The rise and decline of [Ca2+](i) was preceded by a transient increase in total calcium. If stimulation was terminated after 7-8 wk when an essentially complete fast-to-slow transformation had taken place, a subsequent rest period led to a reverse slow-to-fast transformation, which was also preceded by a transient increase of [Ca2+](i) reaching a peak at day 5 of rest. Unstimulated fast and slow fibers and fully transformed fibers do not differ in their [Ca2+] levels; thus it appears that the transformation process itself is accompanied, particularly in its earlier stages, by elevated [Ca2+](i) levels. Elucidation of the relation between changes in Ca2+ and changes in gene expression will require further work.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Cell Physiology |
| Volume | 253 |
| Issue number | 2 |
| State | Published - 1987 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Cell Biology
- Clinical Biochemistry
- Physiology
Cite this
Changes in intracellular ionized Ca concentration associated with muscle fiber type transformation. / Sreter, F. A.; Lopez, J. R.; Alamo, L.; Mabuchi, K.; Gergely, J.
In: American Journal of Physiology - Cell Physiology, Vol. 253, No. 2, 1987.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Changes in intracellular ionized Ca concentration associated with muscle fiber type transformation
AU - Sreter, F. A.
AU - Lopez, J. R.
AU - Alamo, L.
AU - Mabuchi, K.
AU - Gergely, J.
PY - 1987
Y1 - 1987
N2 - Since increased muscle activity, which results in fast-slow fiber transformation, is associated with increases in sarcoplasmic Ca2+ concentration ([Ca2+](i)), it seemed of interest to study the level of [Ca2+] after cessation of stimulation in fibers of the extensor digitorum longus muscle chronically stimulated (8 Hz). [Ca2+](i) was measured in individual fibers with a Ca2+-sensitive electrode after subtracting the membrane potential, measured simultaneously from the potential of the Ca2+ electrode. During the first 14 days of stimulation, [Ca2+](i) increased from ~0.1 to 0.5 μM and declined in ~3 wk to a value slightly higher than the initial one. The rise and decline of [Ca2+](i) was preceded by a transient increase in total calcium. If stimulation was terminated after 7-8 wk when an essentially complete fast-to-slow transformation had taken place, a subsequent rest period led to a reverse slow-to-fast transformation, which was also preceded by a transient increase of [Ca2+](i) reaching a peak at day 5 of rest. Unstimulated fast and slow fibers and fully transformed fibers do not differ in their [Ca2+] levels; thus it appears that the transformation process itself is accompanied, particularly in its earlier stages, by elevated [Ca2+](i) levels. Elucidation of the relation between changes in Ca2+ and changes in gene expression will require further work.
AB - Since increased muscle activity, which results in fast-slow fiber transformation, is associated with increases in sarcoplasmic Ca2+ concentration ([Ca2+](i)), it seemed of interest to study the level of [Ca2+] after cessation of stimulation in fibers of the extensor digitorum longus muscle chronically stimulated (8 Hz). [Ca2+](i) was measured in individual fibers with a Ca2+-sensitive electrode after subtracting the membrane potential, measured simultaneously from the potential of the Ca2+ electrode. During the first 14 days of stimulation, [Ca2+](i) increased from ~0.1 to 0.5 μM and declined in ~3 wk to a value slightly higher than the initial one. The rise and decline of [Ca2+](i) was preceded by a transient increase in total calcium. If stimulation was terminated after 7-8 wk when an essentially complete fast-to-slow transformation had taken place, a subsequent rest period led to a reverse slow-to-fast transformation, which was also preceded by a transient increase of [Ca2+](i) reaching a peak at day 5 of rest. Unstimulated fast and slow fibers and fully transformed fibers do not differ in their [Ca2+] levels; thus it appears that the transformation process itself is accompanied, particularly in its earlier stages, by elevated [Ca2+](i) levels. Elucidation of the relation between changes in Ca2+ and changes in gene expression will require further work.
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M3 - Article
VL - 253
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6143
IS - 2
ER -