Ca2+ release channels in rat denervated skeletal muscles
Sarcoplasmic reticulum (SR) Ca2+ release channel-ryanodine receptors (RYR1) from rat fast-twitch skeletal muscle were studied by incorporating heavy sarcoplasmic reticulum membranes into a lipid bilayer. Channels from normal and denervated muscles had the same conductance as that reported for rabbit...
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Published in | Experimental physiology Vol. 80; no. 4; pp. 561 - 574 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
England
The Physiological Society
01.07.1995
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Subjects | |
Online Access | Get full text |
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Summary: | Sarcoplasmic reticulum (SR) Ca2+ release channel-ryanodine receptors (RYR1) from rat fast-twitch skeletal muscle were studied
by incorporating heavy sarcoplasmic reticulum membranes into a lipid bilayer. Channels from normal and denervated muscles
had the same conductance as that reported for rabbits (about 500 pS) in 250:250 mM cis:trans caesium methanesulphonate. Caffeine
(0.1 mM) induced a larger increase in the open probability (Po) in denervated than in normal channels. The caffeine effect
was caused by changes in mean open and burst time distributions. Longer opening and burst events were detected in the presence
of caffeine. High caffeine concentrations (4 mM) gave similar results in channels from normal and denervated muscles. In denervated
muscle, unlike intact muscle, the Ca2+ release channel was not activated at millimolar Ca2+ concentrations; this is similar
to the cardiac isoform of the channel. Maximal channel activation was shifted to higher Ca2+ concentrations (pCa 4) and the
channel remained activated at millimolar Ca2+ concentrations. The main effect of millimolar Ca2+ concentrations upon Ca2+
release channels from denervated muscles was an increase in the mean open time, with a concomitant increment of the mean burst
duration. Alterations in channel gating properties in calcium and caffeine account for changes in the mechanical response
after skeletal muscle denervation. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0958-0670 1469-445X |
DOI: | 10.1113/expphysiol.1995.sp003867 |