scholarly journals Normal myogenic cells from newborn mice restore normal histology to degenerating muscles of the mdx mouse.

1990 ◽  
Vol 111 (6) ◽  
pp. 2437-2449 ◽  
Author(s):  
J E Morgan ◽  
E P Hoffman ◽  
T A Partridge
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Mdx Mouse ◽  
Newborn Mouse ◽  
Normal Muscle ◽  
Newborn Mice ◽  
X Ray ◽  
Dystrophin Deficiency ◽  
Regenerated Fibers ◽  
Muscle Precursor Cells

Dystrophin deficiency in skeletal muscle of the x-linked dystrophic (mdx) mouse can be partially remedied by implantation of normal muscle precursor cells (mpc) (Partridge, T. A., J. E. Morgan, G. R. Coulton, E. P. Hoffman, and L. M. Kunkel. 1989. Nature (Lond.). 337:176-179). However, it is difficult to determine whether this biochemical "rescue" results in any improvement in the structure or function of the treated muscle, because the vigorous regeneration of mdx muscle more than compensates for the degeneration (Coulton, G. R., N. A. Curtin, J. E. Morgan, and T. A. Partridge. 1988. Neuropathol. Appl. Neurobiol. 14:299-314). By using x-ray irradiation to prevent mpc proliferation, it is possible to study loss of mdx muscle fibers without the complicating effect of simultaneous fiber regeneration. Thus, improvements in fiber survival resulting from any potential therapy can be detected easily (Wakeford, S., D. J. Watt, and T. A. Patridge. 1990. Muscle & Nerve.) Here, we have implanted normal mpc, obtained from newborn mice, into such preirradiated mdx muscles, finding that it is far more extensively permeated and replaced by implanted mpc than is nonirradiated mdx muscle; this is evident both from analysis of glucose-6-phosphate isomerase isoenzyme markers and from immunoblots and immunostaining of dystrophin in the treated muscles. Incorporation of normal mpc markedly reduces the loss of muscle fibers and the deterioration of muscle structure which otherwise occurs in irradiated mdx muscles. Surprisingly, the regenerated fibers are largely peripherally nucleated, whereas regenerated mouse skeletal muscle fibers are normally centrally nucleated. We attribute this regeneration of apparently normal muscle to the tendency of newborn mouse mpc to recapitulate their neonatal ontogeny, even when grafted into 3-wk-old degenerating muscle.

scholarly journals Role of Nebulin on Actomyosin Interaction Studied in situ in Demembranated Skeletal Muscle Fibers from Newborn Mice

2009 ◽  
Vol 96 (3) ◽  
pp. 127a
Author(s):  
M.L. Bang ◽  
M. Caremani ◽  
E. Brunello ◽  
R. Littlefield ◽  
R. Lieber ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Newborn Mice ◽  
Skeletal Muscle Fibers ◽  
Actomyosin Interaction

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

2003 ◽  
Vol 285 (3) ◽  
pp. C522-C528 ◽  
Author(s):  
David R. Plant ◽  
Gordon S. Lynch
Keyword(s):  
Muscle Fibers ◽  
Voltage Regulation ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Channel Activity ◽  
Release Channel ◽  
Transverse Tubular System ◽  
Skinned Muscle ◽  
Dystrophin Deficiency ◽  
And Control

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.

scholarly journals Backward Movements of Cross-Bridges by Application of Stretch and by Binding of MgADP to Skeletal Muscle Fibers in the Rigor State as Studied by X-Ray Diffraction

1999 ◽  
Vol 76 (4) ◽  
pp. 1770-1783 ◽  
Author(s):  
Yasunori Takezawa ◽  
Duck-Sool Kim ◽  
Masaki Ogino ◽  
Yasunobu Sugimoto ◽  
Takakazu Kobayashi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rigor State ◽  
Skeletal Muscle Fibers ◽  
Cross Bridges

scholarly journals Sarcomere-Length Dependence of the Low Angle X-Ray Pattern from Skeletal Muscle Fibers at Rest and during Isometric Contraction

2012 ◽  
Vol 102 (3) ◽  
pp. 147a-148a
Author(s):  
Gabriella Piazzesi ◽  
Massimo Reconditi ◽  
Elisabetta Brunello ◽  
Luca Fusi ◽  
Marco Linari ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Isometric Contraction ◽  
Sarcomere Length ◽  
Muscle Fibers ◽  
X Ray ◽  
Length Dependence ◽  
Skeletal Muscle Fibers

scholarly journals Extensive but Coordinated Reorganization of the Membrane Skeleton in Myofibers of Dystrophic (mdx) Mice

1999 ◽  
Vol 144 (6) ◽  
pp. 1259-1270 ◽  
Author(s):  
McRae W. Williams ◽  
Robert J. Bloch
Keyword(s):  
Skeletal Muscle ◽  
Membrane Proteins ◽  
Muscle Fibers ◽  
Membrane Skeleton ◽  
Confocal Imaging ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Intracellular Membrane ◽  
Dystrophic Muscle ◽  
Dihydropyridine Receptors

We used immunofluorescence techniques and confocal imaging to study the organization of the membrane skeleton of skeletal muscle fibers of mdx mice, which lack dystrophin. β-Spectrin is normally found at the sarcolemma in costameres, a rectilinear array of longitudinal strands and elements overlying Z and M lines. However, in the skeletal muscle of mdx mice, β-spectrin tends to be absent from the sarcolemma over M lines and the longitudinal strands may be disrupted or missing. Other proteins of the membrane and associated cytoskeleton, including syntrophin, β-dystroglycan, vinculin, and Na,K-ATPase are also concentrated in costameres, in control myofibers, and mdx muscle. They also distribute into the same altered sarcolemmal arrays that contain β-spectrin. Utrophin, which is expressed in mdx muscle, also codistributes with β-spectrin at the mutant sarcolemma. By contrast, the distribution of structural and intracellular membrane proteins, including α-actinin, the Ca-ATPase and dihydropyridine receptors, is not affected, even at sites close to the sarcolemma. Our results suggest that in myofibers of the mdx mouse, the membrane- associated cytoskeleton, but not the nearby myoplasm, undergoes widespread coordinated changes in organization. These changes may contribute to the fragility of the sarcolemma of dystrophic muscle.

scholarly journals Genetic correction of dystrophin deficiency and skeletal muscle remodeling in adult MDX mouse via transplantation of retroviral producer cells.

1997 ◽  
Vol 100 (3) ◽  
pp. 620-628 ◽  
Author(s):  
A Fassati ◽  
D J Wells ◽  
P A Sgro Serpente ◽  
F S Walsh ◽  
S C Brown ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Mdx Mouse ◽  
Dystrophin Deficiency ◽  
Muscle Remodeling

Quantitative x-ray elemental imaging in stimulated single intact skeletal muscle fibers: The fate of calcium in the presence of ryanodine

1988 ◽  
Vol 46 ◽  
pp. 90-91
Author(s):  
J. Sommer ◽  
P. Ingram ◽  
A. LeFurgey ◽  
R. Nassar ◽  
T. High
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Time Course ◽  
Imaging System ◽  
Quantitative Imaging ◽  
Muscle Fibers ◽  
Frog Skeletal Muscle ◽  
X Ray ◽  
Skeletal Muscle Fibers ◽  
Freeze Dried

We are involved in a continuing series of experiments aimed at a complete description,in terms of morphology and quantitative topochemistry, of the time course of spatial distributions of physiologically important elements during excitation-contraction coupling (ECC) at different time intervals (fractions of msec) following electrical stimulation of single, intact frog skeletal muscle fibers. In this present study wg report such distributions for Ca after 1,2 and 3 min of electrical stimulation in the presence of 2x10-4 M ryanodine, an alkaloid that, in time, causes irreversible muscle contractures.Single, intact frog skeletal muscle fibers were quick-frozen, cryosectioned, freeze-substituted and in one case freeze-fractured. The freeze-dried cryosections were subjected to electron probe X-ray microanalysis (EPXMA) in a JEOL 1200EX analytical electron microscope equipped with a Tracor Northern X-ray detector and a fully quantitative imaging system. Both, 64/64 pixel images (ambient temp.), and small raster probes (cold stage,-115 °C) for better statistics, were obtained, each from the same section.

Upregulation of store-operated Ca2+ entry in dystrophic mdx mouse muscle

2010 ◽  
Vol 299 (1) ◽  
pp. C42-C50 ◽  
Author(s):  
Joshua N. Edwards ◽  
Oliver Friedrich ◽  
Tanya R. Cully ◽  
Frederic von Wegner ◽  
Robyn M. Murphy ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Mdx Mouse ◽  
Cell Necrosis ◽  
Wild Type ◽  
Dystrophic Muscle ◽  
Adult Skeletal Muscle ◽  
Mouse Muscle ◽  
Threefold Increase ◽  
Tubular System

Store-operated Ca2+ entry (SOCE) is an important mechanism in virtually all cells. In adult skeletal muscle, this mechanism is highly specialized for the rapid delivery of Ca2+ from the transverse tubule into the junctional cleft during periods of depleting Ca2+ release. In dystrophic muscle fibers, SOCE may be a source of Ca2+ overload, leading to cell necrosis. However, this possibility is yet to be examined in an adult fiber during Ca2+ release. To examine this, Ca2+ in the tubular system and cytoplasm were simultaneously imaged during direct release of Ca2+ from sarcoplasmic reticulum (SR) in skeletal muscle fibers from healthy (wild-type, WT) and dystrophic mdx mouse. The mdx fibers were found to have normal activation and deactivation properties of SOCE. However, a depression of the cytoplasmic Ca2+ transient in mdx compared with WT fibers was observed, as was a shift in the SOCE activation and deactivation thresholds to higher SR Ca2+ concentrations ([Ca2+]SR). The shift in SOCE activation and deactivation thresholds was accompanied by an approximately threefold increase in STIM1 and Orai1 proteins in dystrophic muscle. While the mdx fibers can introduce more Ca2+ into the fiber for an equivalent depletion of [Ca2+]SR via SOCE, it remains unclear whether this is deleterious.

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