|
rdf:type |
|
|
lifeskim:mentions |
umls-concept:C0030685,
umls-concept:C0034650,
umls-concept:C0036226,
umls-concept:C0205359,
umls-concept:C0242692,
umls-concept:C0376249,
umls-concept:C0391871,
umls-concept:C0441471,
umls-concept:C0596235,
umls-concept:C0680255,
umls-concept:C1283071,
umls-concept:C1709059,
umls-concept:C1963578,
umls-concept:C2346927
|
|
pubmed:issue |
2
|
|
pubmed:dateCreated |
1998-3-5
|
|
pubmed:abstractText |
The modulation by internal free [Mg2+] of spontaneous calcium release events (Ca2+ "sparks") from the sarcoplasmic reticulum (SR) was studied in depolarized notched frog skeletal muscle fibers using a laser scanning confocal microscope in line-scan mode (x vs. t). Over the range of [Mg2+] from 0.13 to 1.86 mM, decreasing the [Mg2+] induced an increase in the frequency of calcium release events in proportion to [Mg2+]-1.6. The change of event frequency was not due to changes in [Mg-ATP] or [ATP]. Analysis of individual SR calcium release event properties showed that the variation in event frequency induced by the change of [Mg2+] was not accompanied by any changes in the spatiotemporal spread (i.e., spatial half width or temporal half duration) of Ca2+ sparks. The increase in event frequency also had no effect on the distribution of event amplitudes. Finally, the rise time of calcium sparks was independent of the [Mg2+], indicating that the open time of the SR channel or channels underlying spontaneous calcium release events was not altered by [Mg2+] over the range tested. These results suggest that in resting skeletal fibers, [Mg2+] modulates the SR calcium release channel opening frequency by modifying the average closed time of the channel without altering the open time. A kinetic reaction scheme consistent with our results and those of bilayer and SR vesicle experiments indicates that physiological levels of resting Mg2+ may inhibit channel opening by occupying the site for calcium activation of the SR calcium release channel.
|
|
pubmed:grant |
|
|
pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-1326044,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-1331805,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-14114498,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-1512554,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-1512555,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-1708823,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-2057528,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-2410798,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-2412607,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-2422165,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-2431098,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-2537030,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-2613883,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-2848455,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-2849609,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-3754147,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-5409477,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-5456208,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-6698971,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-7510773,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-7516645,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-7569901,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-7858121,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-7965848,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8010748,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8235594,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8405464,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8537819,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8559251,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8605229,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8842211,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8889203,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8943948,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-8968567,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-9003545,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-9096063,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-9379173,
http://linkedlifedata.com/resource/pubmed/commentcorrection/9450940-9380759
|
|
pubmed:language |
eng
|
|
pubmed:journal |
|
|
pubmed:citationSubset |
IM
|
|
pubmed:chemical |
|
|
pubmed:status |
MEDLINE
|
|
pubmed:month |
Feb
|
|
pubmed:issn |
0022-1295
|
|
pubmed:author |
|
|
pubmed:issnType |
Print
|
|
pubmed:volume |
111
|
|
pubmed:owner |
NLM
|
|
pubmed:authorsComplete |
Y
|
|
pubmed:pagination |
207-24
|
|
pubmed:dateRevised |
2009-11-18
|
|
pubmed:meshHeading |
pubmed-meshheading:9450940-Adenine Nucleotides,
pubmed-meshheading:9450940-Animals,
pubmed-meshheading:9450940-Calcium,
pubmed-meshheading:9450940-Electrophysiology,
pubmed-meshheading:9450940-Image Cytometry,
pubmed-meshheading:9450940-Image Processing, Computer-Assisted,
pubmed-meshheading:9450940-Kinetics,
pubmed-meshheading:9450940-Magnesium,
pubmed-meshheading:9450940-Microscopy, Confocal,
pubmed-meshheading:9450940-Muscle, Skeletal,
pubmed-meshheading:9450940-Muscle Fibers, Skeletal,
pubmed-meshheading:9450940-Rana pipiens,
pubmed-meshheading:9450940-Ryanodine Receptor Calcium Release Channel,
pubmed-meshheading:9450940-Sarcoplasmic Reticulum,
pubmed-meshheading:9450940-Spectrometry, Fluorescence
|
|
pubmed:year |
1998
|
|
pubmed:articleTitle |
Modulation of the frequency of spontaneous sarcoplasmic reticulum Ca2+ release events (Ca2+ sparks) by myoplasmic [Mg2+] in frog skeletal muscle.
|
|
pubmed:affiliation |
Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
|
|
pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
|
