Intracellular calcium signals measured with indo‐1 in isolated skeletal muscle fibres from control and <i>mdx</i> mice

Collet, Claude; Allard, Bruno; Tourneur, Yves; Jacquemond, Vincent

doi:10.1111/j.1469-7793.1999.00417.x

Cited by 65 publications

(82 citation statements)

References 29 publications

(54 reference statements)

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“…Basal cytosolic Ca 2+ concentrations were very similar in normal and dystrophic FDB fibers, in agreement with previous reports (Collet et al, 1999;De Backer et al, 2002;Tutdibi et al, 1999;Vandebrouck et al, 2002). Peak values of cytosolic Ca 2+ transients triggered by KCl depolarization were also not significantly different between C57BL/6J and mdx 5cv fibers in both normal and Ca 2+ -free solution, suggesting that mechanisms involved in Ca 2+ release are not altered in dystrophic fibers, as previously reported for electrically-evoked Ca 2+ transients (Collet et al, 1999;Gillis, 1996;Plant and Lynch, 2003;Tutdibi et al, 1999).…”

Section: Discussionsupporting

confidence: 80%

“…Peak values of cytosolic Ca 2+ transients triggered by KCl depolarization were also not significantly different between C57BL/6J and mdx 5cv fibers in both normal and Ca 2+ -free solution, suggesting that mechanisms involved in Ca 2+ release are not altered in dystrophic fibers, as previously reported for electrically-evoked Ca 2+ transients (Collet et al, 1999;Gillis, 1996;Plant and Lynch, 2003;Tutdibi et al, 1999).…”

Section: Discussionsupporting

confidence: 62%

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Ca2+-independent phospholipase A2 enhances store-operated Ca2+ entry in dystrophic skeletal muscle fibers

Boittin

Petermann

Hirn

et al. 2006

Journal of Cell Science

112

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Duchenne muscular dystrophy is caused by deficiency of dystrophin and leads to progressive weakness. It has been proposed that the muscle degeneration occurring in this disease is caused by increased Ca2+ influx due to enhanced activity of cationic channels that are activated either by stretch of the plasma membrane (stretch-activated channels) or by Ca2+-store depletion (store-operated channels). Using both cytosolic Ca2+ measurements with Fura-2 and the manganese quench method, we show here that store-operated Ca2+ entry is greatly enhanced in dystrophic skeletal flexor digitorum brevis fibers isolated from mdx5cv mice, a mouse model of Duchenne muscular dystrophy. Moreover, we show for the first time that store-operated Ca2+ entry in these fibers is under the control of the Ca2+-independent phospholipase A2 and that the exaggerated Ca2+ influx can be completely attenuated by inhibitors of this enzyme. Enhanced store-operated Ca2+ entry in dystrophic fibers is likely to be due to a near twofold overexpression of Ca2+-independent phospholipase A2. The Ca2+-independent phospholipase A2 pathway therefore appears as an attractive target to reduce excessive Ca2+ influx and subsequent degeneration occurring in dystrophic fibers.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionsupporting

confidence: 62%

Ca2+-independent phospholipase A2 enhances store-operated Ca2+ entry in dystrophic skeletal muscle fibers

Boittin

Petermann

Hirn

et al. 2006

Journal of Cell Science

112

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“…Our finding of a decreased sensitivity of the Ca 2ϩ release channel (when stimulated by caffeine) is in contrast to previous reports of normal electrically elicited Ca 2ϩ transients in muscles from mdx mice (4,14,35). Data on caffeine-induced contraction in saponinskinned single fibers from mdx mice are conflicting, with either an increase or decrease in the amplitude of caffeine-induced contraction being reported (8,33).…”

Section: Discussioncontrasting

confidence: 56%

Depolarization-induced contraction and SR function in mechanically skinned muscle fibers from dystrophic mdx mice

Plant

Lynch

2003

American Journal of Physiology-Cell Physiology

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Dystrophin is absent in muscle fibers of patients with Duchenne muscular dystrophy (DMD) and in muscle fibers from the mdx mouse, an animal model of DMD. Disrupted excitation-contraction (E-C) coupling has been postulated to be a functional consequence of the lack of dystrophin, although the evidence for this is not entirely clear. We used mechanically skinned fibers (with a sealed transverse tubular system) prepared from fast extensor digitorum longus muscles of wild-type control and dystrophic mdx mice to test the hypothesis that dystrophin deficiency would affect the depolarization-induced contractile response (DICR) and sarcoplasmic reticulum (SR) function. DICR was similar in muscle fibers from mdx and control mice, indicating normal voltage regulation of Ca2+ release. Nevertheless, rundown of DICR (<50% of initial) was reached more rapidly in fibers from mdx than control mice [control: 32 ± 5 depolarizations ( n = 14 fibers) vs. mdx: 18 ± 1 depolarizations ( n = 7) before rundown, P < 0.05]. The repriming rate for DICRs was decreased in fibers from mdx mice, with lower submaximal DICR observed after 5, 10, and 20 s of repriming compared with fibers from control mice ( P < 0.05). SR Ca2+ reloading was not different in fibers from control and mdx mice, and no difference was observed in SR Ca2+ leak. Caffeine (2–7 mM)-induced contraction was diminished in fibers from mdx mice compared with control ( P < 0.05), indicating depressed SR Ca2+ release channel activity. Our findings indicate that fast fibers from mdx mice exhibit some impairment in the events mediating E-C coupling and SR Ca2+ release channel activity.

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“…Experiments were performed on single skeletal fibers from the FDB and interosseus muscles using previously described methods and analytical procedures (42)(43)(44), see SI Methods for further details.…”

Section: Electrophysiology and Intracellular Calcium Measurementsmentioning

confidence: 99%

T-tubule disorganization and defective excitation-contraction coupling in muscle fibers lacking myotubularin lipid phosphatase

Al‐Qusairi

Weiss

Toussaint

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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165

199

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Skeletal muscle contraction is triggered by the excitation-contraction (E-C) coupling machinery residing at the triad, a membrane structure formed by the juxtaposition of T-tubules and sarcoplasmic reticulum (SR) cisternae. The formation and maintenance of this structure is key for muscle function but is not well characterized. We have investigated the mechanisms leading to X-linked myotubular myopathy (XLMTM), a severe congenital disorder due to loss of function mutations in the MTM1 gene, encoding myotubularin, a phosphoinositide phosphatase thought to have a role in plasma membrane homeostasis and endocytosis. Using a mouse model of the disease, we report that Mtm1-deficient muscle fibers have a decreased number of triads and abnormal longitudinally oriented T-tubules. In addition, SR Ca 2؉ release elicited by voltageclamp depolarizations is strongly depressed in myotubularin-deficient muscle fibers, with myoplasmic Ca 2؉ removal and SR Ca 2؉ content essentially unaffected. At the molecular level, Mtm1-deficient myofibers exhibit a 3-fold reduction in type 1 ryanodine receptor (RyR1) protein level. These data reveal a critical role of myotubularin in the proper organization and function of the E-C coupling machinery and strongly suggest that defective RyR1-mediated SR Ca 2؉ release is responsible for the failure of muscle function in myotubular myopathy. myotubular myopathy ͉ triad

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Intracellular calcium signals measured with indo‐1 in isolated skeletal muscle fibres from control and mdx mice

Cited by 65 publications

References 29 publications

Ca2+-independent phospholipase A2 enhances store-operated Ca2+ entry in dystrophic skeletal muscle fibers

Ca2+-independent phospholipase A2 enhances store-operated Ca2+ entry in dystrophic skeletal muscle fibers

Depolarization-induced contraction and SR function in mechanically skinned muscle fibers from dystrophic mdx mice

T-tubule disorganization and defective excitation-contraction coupling in muscle fibers lacking myotubularin lipid phosphatase

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