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Single-channel properties of the sarcoplasmic reticulum calcium-release channel in slow- and fast-twitch muscles of Rhesus monkeys.

Authors
  • Bastide, B
  • Mounier, Y
Type
Published Article
Journal
Pflügers Archiv : European journal of physiology
Publication Date
Aug 01, 1998
Volume
436
Issue
3
Pages
485–488
Identifiers
PMID: 9644234
Source
Medline
License
Unknown

Abstract

RyR1 is the main isoform of ryanodine receptor expressed in fast- and slow-twitch mammalian skeletal muscles although differences in Ca2+-release kinetics and properties have been reported. Single-channel measurements reveal that a large proportion (82%) of Ca2+-release channels measured in slow-twitch muscle preparations have properties similar to those of the Ca2+-release channels of fast-twitch preparations, i.e. the same conductance, an identical sensitivity to caffeine and a bell-shaped Ca2+ activation curve for pCa (-log10[Ca2+]) 7 to 3. A low proportion (18%) of Ca2+-release channels observed in preparations from slow-twitch muscles were characterized by a very high activity level. These channels were not inhibited at a millimolar concentration of Ca2+. Our data suggest that the different properties of Ca2+ release in slow- and fast-twitch muscles might not be related to intrinsic properties of the Ca2+-release channels of each type of muscle but rather to the co-expression of two isoforms of ryanodine receptor and the lower amount of Ca2+-release channels expressed in slow- than in fast-twitch muscles.

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