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Propagation in the transverse tubular system and voltage dependence of calcium release in normal and mdx mouse muscle fibres
Author(s) -
Woods Christopher E.,
Novo David,
DiFranco Marino,
Capote Joana,
Vergara Julio L.
Publication year - 2005
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2005.089318
Subject(s) - endoplasmic reticulum , biophysics , chemistry , skeletal muscle , egta , voltage clamp , stimulation , contraction (grammar) , duchenne muscular dystrophy , calcium , anatomy , medicine , membrane potential , endocrinology , biology , biochemistry , organic chemistry
Using a two‐microelectrode voltage clamp technique, we investigated possible mechanisms underlying the impaired excitation–contraction coupling in skeletal muscle fibres of the mdx mouse, a model of the human disease Duchenne muscular dystrophy. We evaluated the role of the transverse tubular system (T‐system) by using the potentiometric indicator di‐8 ANEPPS, and that of the sarcoplasmic reticulum (SR) Ca 2 + release by measuring Ca 2 + transients with a low affinity indicator in the presence of high EGTA concentrations under voltage clamp conditions. We observed minimal differences in the T‐system structure and the T‐system electrical propagation was not different between normal and mdx mice. Whereas the maximum Ca 2 + release elicited by voltage pulses was reduced by ∼67% in mdx fibres, in agreement with previous results obtained using AP stimulation, the voltage dependence of SR Ca 2 + release was identical to that seen in normal fibres. Taken together, our data suggest that the intrinsic ability of the sarcoplasmic reticulum to release Ca 2 + may be altered in the mdx mouse.