| First Author | Woods CE | Year | 2004 |
| Journal | J Physiol | Volume | 557 |
| Issue | Pt 1 | Pages | 59-75 |
| PubMed ID | 15004213 | Mgi Jnum | J:105267 |
| Mgi Id | MGI:3614594 | Doi | 10.1113/jphysiol.2004.061291 |
| Citation | Woods CE, et al. (2004) The action potential-evoked sarcoplasmic reticulum calcium release is impaired in mdx mouse muscle fibres. J Physiol 557(Pt 1):59-75 |
| abstractText | The mdx mouse, a model of the human disease Duchenne muscular dystrophy, has skeletal muscle fibres which display incompletely understood impaired contractile function. We explored the possibility that action potential-evoked Ca(2+) release is altered in mdx fibres. Action potential-evoked Ca(2+)-dependent fluorescence transients were recorded, using both low and high affinity Ca(2+) indicators, from enzymatically isolated fibres obtained from extensor digitorum longus (EDL) and flexor digitorum brevis (FDB) muscles of normal and mdx mice. Fibres were immobilized using either intracellular EGTA or N-benzyl-p-toluene sulphonamide, an inhibitor of the myosin II ATPase. We found that the amplitude of the action potential-evoked Ca(2+) transients was significantly decreased in mdx mice with no measured difference in that of the surface action potential. In addition, Ca(2+) transients recorded from mdx fibres in the absence of EGTA also displayed a marked prolongation of the slow decay phase. Model simulations of the action potential-evoked transients in the presence of high EGTA concentrations suggest that the reduction in the evoked sarcoplasmic reticulum Ca(2+) release flux is responsible for the decrease in the peak of the Ca(2+) transient in mdx fibres. Since the myoplasmic Ca(2+) concentration is a critical regulator of muscle contraction, these results may help to explain the weakness observed in skeletal muscle fibres from mdx mice and, possibly, Duchenne muscular dystrophy patients. |
