Abstract
In many types of muscle, intracellular Ca2+ release for contraction consists of brief Ca2+ sparks. Whether these result from the opening of one or many channels in the sarcoplasmic reticulum is not known. Examining massive numbers of sparks from frog skeletal muscle and evaluating their Ca2+ release current, we provide evidence that they are generated by multiple channels. A mode is demonstrated in the distribution of spark rise times in the presence of the channel activator caffeine. This finding contradicts expectations for single channels evolving reversibly, but not for channels in a group, which collectively could give rise to a stereotyped spark. The release channel agonists imperatoxin A, ryanodine, and bastadin 10 elicit fluorescence events that start with a spark, then decay to steady levels roughly proportional to the unitary conductances of 35%, 50%, and 100% that the agonists, respectively, promote in bilayer experiments. This correspondence indicates that the steady phase is produced by one open channel. Calculated Ca2+ release current decays 10- to 20-fold from spark to steady phase, which requires that six or more channels be open during the spark.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4380-4385 |
| Number of pages | 6 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 97 |
| Issue number | 8 |
| DOIs | |
| State | Published - Apr 11 2000 |
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Keywords
- Bastadin
- Caffeine
- Excitation-contraction coupling
- Ryanodine receptors
- Sarcoplasmic reticulum
ASJC Scopus subject areas
- Genetics
- General
Cite this
Involvement of multiple intracellular release channels in calcium sparks of skeletal muscle. / González, A.; Kirsch, W. G.; Shirokova, N.; Pizarro, G.; Brum, G.; Pessah, Isaac N; Stern, M. D.; Cheng, H.; Ríos, E.
In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 97, No. 8, 11.04.2000, p. 4380-4385.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Involvement of multiple intracellular release channels in calcium sparks of skeletal muscle
AU - González, A.
AU - Kirsch, W. G.
AU - Shirokova, N.
AU - Pizarro, G.
AU - Brum, G.
AU - Pessah, Isaac N
AU - Stern, M. D.
AU - Cheng, H.
AU - Ríos, E.
PY - 2000/4/11
Y1 - 2000/4/11
N2 - In many types of muscle, intracellular Ca2+ release for contraction consists of brief Ca2+ sparks. Whether these result from the opening of one or many channels in the sarcoplasmic reticulum is not known. Examining massive numbers of sparks from frog skeletal muscle and evaluating their Ca2+ release current, we provide evidence that they are generated by multiple channels. A mode is demonstrated in the distribution of spark rise times in the presence of the channel activator caffeine. This finding contradicts expectations for single channels evolving reversibly, but not for channels in a group, which collectively could give rise to a stereotyped spark. The release channel agonists imperatoxin A, ryanodine, and bastadin 10 elicit fluorescence events that start with a spark, then decay to steady levels roughly proportional to the unitary conductances of 35%, 50%, and 100% that the agonists, respectively, promote in bilayer experiments. This correspondence indicates that the steady phase is produced by one open channel. Calculated Ca2+ release current decays 10- to 20-fold from spark to steady phase, which requires that six or more channels be open during the spark.
AB - In many types of muscle, intracellular Ca2+ release for contraction consists of brief Ca2+ sparks. Whether these result from the opening of one or many channels in the sarcoplasmic reticulum is not known. Examining massive numbers of sparks from frog skeletal muscle and evaluating their Ca2+ release current, we provide evidence that they are generated by multiple channels. A mode is demonstrated in the distribution of spark rise times in the presence of the channel activator caffeine. This finding contradicts expectations for single channels evolving reversibly, but not for channels in a group, which collectively could give rise to a stereotyped spark. The release channel agonists imperatoxin A, ryanodine, and bastadin 10 elicit fluorescence events that start with a spark, then decay to steady levels roughly proportional to the unitary conductances of 35%, 50%, and 100% that the agonists, respectively, promote in bilayer experiments. This correspondence indicates that the steady phase is produced by one open channel. Calculated Ca2+ release current decays 10- to 20-fold from spark to steady phase, which requires that six or more channels be open during the spark.
KW - Bastadin
KW - Caffeine
KW - Excitation-contraction coupling
KW - Ryanodine receptors
KW - Sarcoplasmic reticulum
UR - http://www.scopus.com/inward/record.url?scp=0034636159&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034636159&partnerID=8YFLogxK
U2 - 10.1073/pnas.070056497
DO - 10.1073/pnas.070056497
M3 - Article
C2 - 10759554
AN - SCOPUS:0034636159
VL - 97
SP - 4380
EP - 4385
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 8
ER -