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 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 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.

Elevated MMP2 abundance and activity in mdx mice are alleviated by prenatal taurine supplementation

2020 ◽  
Vol 318 (6) ◽  
pp. C1083-C1091
Author(s):  
Xiaoyu Ren ◽  
Hongyang Xu ◽  
Robert G. Barker ◽  
Graham D. Lamb ◽  
Robyn M. Murphy
Keyword(s):  
Muscle Fibers ◽  
Muscle Growth ◽  
Early Death ◽  
Active Role ◽  
Matrix Metalloproteinase 2 ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Taurine Supplementation ◽  
Naturally Occurring ◽  
Age Related

Duchenne muscular dystrophy (DMD) is a severe, progressive muscle-wasting disorder that leads to early death. The mdx mouse is a naturally occurring mutant model for DMD. It lacks dystrophin and displays peak muscle cell necrosis at ~28 days (D28), but in contrast to DMD, mdx mice experience muscle regeneration by D70. We hypothesized that matrix metalloproteinase-2 (MMP2) and/or MMP9 play key roles in the degeneration/regeneration phases in mdx mice. MMP2 abundance in muscle homogenates, measured by calibrated Western blotting, and activity, measured by zymogram, were lower at D70 compared with D28 in both mdx and wild-type (WT) mice. Importantly, MMP2 abundance was higher in both D28 and D70 mdx mice than in age-matched WT mice. The higher MMP2 abundance was not due to infiltrating macrophages, because MMP2 content was still higher in isolated muscle fibers where most macrophages had been removed. Prenatal supplementation with the amino acid taurine, which improved muscle strength in D28 mdx mice, produced approximately twofold lower MMP2 activity, indicating that increased MMP2 abundance is not required when muscle damage is attenuated. There was no difference in MMP9 abundance between age-matched WT and mdx mice ( P > 0.05). WT mice displayed decreased MMP9 abundance as they aged. While MMP9 may have a role during age-related skeletal muscle growth, it does not appear essential for degeneration/regeneration cycles in the mdx mouse. Our findings indicate that MMP2 plays a more active role than MMP9 in the degenerative phases of muscle fibers in D28 mdx mice.

Contraction-induced injury to single permeabilized muscle fibers from mdx, transgenic mdx, and control mice

2000 ◽  
Vol 279 (4) ◽  
pp. C1290-C1294 ◽  
Author(s):  
Gordon S. Lynch ◽  
Jill A. Rafael ◽  
Jeffrey S. Chamberlain ◽  
John A. Faulkner
Keyword(s):  
Null Hypothesis ◽  
Fiber Length ◽  
Extensor Digitorum Longus ◽  
Muscle Fibers ◽  
Extensor Digitorum ◽  
Mdx Mice ◽  
And Control ◽  
Permeabilized Fibers ◽  
Permeabilized Muscle ◽  
Sarcolemmal Integrity

Muscle fibers of mdx mice that lack dystrophin are more susceptible to contraction-induced injury, particularly when stretched. In contrast, transgenic mdx (tg -mdx) mice, which overexpress dystrophin, show no morphological or functional signs of dystrophy. Permeabilization disrupts the sarcolemma of fibers from muscles of mdx, tg- mdx, and control mice. We tested the null hypothesis stating that, after single stretches of maximally activated single permeabilized fibers, force deficits do not differ among fibers from extensor digitorum longus muscles of mdx, tg -mdx, or control mice. Fibers were maximally activated by Ca2+ (pCa 4.5) and then stretched through strains of 10%, 20%, or 30% of fiber length ( L f) at a velocity of 0.5 L f/s. Immediately after each strain, the force deficits were not different for fibers from each of the three groups of mice. When collated with studies of membrane-intact fibers in whole muscles of mdx, tg -mdx, and control mice, these results indicate that dystrophic symptoms do not arise from factors within myofibrils but, rather, from disruption of the sarcolemmal integrity that normally provides protection from contraction-induced injury.

scholarly journals Involvement of TRPC in the abnormal calcium influx observed in dystrophic (mdx) mouse skeletal muscle fibers

2002 ◽  
Vol 158 (6) ◽  
pp. 1089-1096 ◽  
Author(s):  
Clarisse Vandebrouck ◽  
Dominique Martin ◽  
Monique Colson-Van Schoor ◽  
Huguette Debaix ◽  
Philippe Gailly
Keyword(s):  
Skeletal Muscle ◽  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Surface Membrane ◽  
Muscle Fibers ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Patch Clamp Technique ◽  
Adult Skeletal Muscle ◽  
Skeletal Muscle Fibers

Duchenne muscular dystrophy results from the lack of dystrophin, a cytoskeletal protein associated with the inner surface membrane, in skeletal muscle. The absence of dystrophin induces an abnormal increase of sarcolemmal calcium influx through cationic channels in adult skeletal muscle fibers from dystrophic (mdx) mice. We observed that the activity of these channels was increased after depletion of the stores of calcium with thapsigargin or caffeine. By analogy with the situation observed in nonexcitable cells, we therefore hypothesized that these store-operated channels could belong to the transient receptor potential channel (TRPC) family. We measured the expression of TRPC isoforms in normal and mdx adult skeletal muscles fibers, and among the seven known isoforms, five were detected (TRPC1, 2, 3, 4, and 6) by RT-PCR. Western blot analysis and immunocytochemistry of normal and mdx muscle fibers demonstrated the localization of TRPC1, 4, and 6 proteins at the plasma membrane. Therefore, an antisense strategy was used to repress these TRPC isoforms. In parallel with the repression of the TRPCs, we observed that the occurrence of calcium leak channels was decreased to one tenth of its control value (patch-clamp technique), showing the involvement of TRPC in the abnormal calcium influx observed in dystrophic fibers.

Eugenol-induced contractions of saponin-skinned fibers are inhibited by heparin or by a ryanodine receptor blocker

2005 ◽  
Vol 83 (12) ◽  
pp. 1093-1100 ◽  
Author(s):  
Marco S. Lofrano-Alves ◽  
Edson L. Oliveira ◽  
Carlos E.N. Damiani ◽  
Ilana Kassouf-Silva ◽  
Rosalvo T.H. Fogaça
Keyword(s):  
Ryanodine Receptor ◽  
Rana Catesbeiana ◽  
Ryanodine Receptors ◽  
Muscle Fibers ◽  
Ruthenium Red ◽  
Muscle Contractions ◽  
Skinned Fibers ◽  
Receptor Blocker ◽  
Release Channel ◽  
Skinned Muscle

The effects of eugenol on the sarcoplasmic reticulum (SR) and contractile apparatus of chemically skinned skeletal muscle fibers of the frog Rana catesbeiana were investigated. In saponin-skinned fibers, eugenol (5 mmol/L) induced muscle contractions, probably by releasing Ca2+ from the SR. The Ca2+-induced Ca2+ release blocker ruthenium red (10 μmol/L) inhibited both caffeine- and eugenol-induced muscle contractions. Ryanodine (200 μmol/L), a specific ryanodine receptor/Ca2+ release channel blocker, promoted complete inhibition of the contractions induced by caffeine, but only partially blocked the contractions induced by eugenol. Heparin (2.5 mg/mL), an inositol 1,4,5-trisphosphate (InsP3) receptor blocker, strongly inhibited the contractions induced by eugenol but had only a small effect on the caffeine-induced contractions. Eugenol neither altered the Ca2+ sensitivity nor the maximal force in Triton X-100 skinned muscle fibers. These data suggest that muscle contraction induced by eugenol involves at least 2 mechanisms of Ca2+ release from the SR: one related to the activation of the ryanodine receptors and another through a heparin-sensitive pathway.

scholarly journals Measuring mitochondrial respiration in intact single muscle fibers

2012 ◽  
Vol 302 (6) ◽  
pp. R712-R719 ◽  
Author(s):  
Rosemary A. Schuh ◽  
Kathryn C. Jackson ◽  
Ramzi J. Khairallah ◽  
Christopher W. Ward ◽  
Espen E. Spangenburg
Keyword(s):  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Mitochondrial Function ◽  
Muscle Fibers ◽  
Peak Oxygen Consumption ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Total Oxygen ◽  
Novel Approach ◽  
Consumption Rates

Measurement of mitochondrial function in skeletal muscle is a vital tool for understanding regulation of cellular bioenergetics. Currently, a number of different experimental approaches are employed to quantify mitochondrial function, with each involving either mechanically or chemically induced disruption of cellular membranes. Here, we describe a novel approach that allows for the quantification of substrate-induced mitochondria-driven oxygen consumption in intact single skeletal muscle fibers isolated from adult mice. Specifically, we isolated intact muscle fibers from the flexor digitorum brevis muscle and placed the fibers in culture conditions overnight. We then quantified oxygen consumption rates using a highly sensitive microplate format. Peak oxygen consumption rates were significantly increased by 3.4-fold and 2.9-fold by simultaneous stimulation with the uncoupling agent, carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP), and/or pyruvate or palmitate exposure, respectively. However, when calculating the total oxygen consumed over the entire treatment, palmitate exposure resulted in significantly more oxygen consumption compared with pyruvate. Further, as proof of principle for the procedure, we isolated fibers from the mdx mouse model, which has known mitochondrial deficits. We found significant reductions in initial and peak oxygen consumption of 51% and 61% compared with fibers isolated from the wild-type (WT) animals, respectively. In addition, we determined that fibers isolated from mdx mice exhibited less total oxygen consumption in response to the FCCP + pyruvate stimulation compared with the WT mice. This novel approach allows the user to make mitochondria-specific measures in a nondisrupted muscle fiber that has been isolated from a whole muscle.

Functional effects of uridine triphosphate on human skinned skeletal muscle fibers

1998 ◽  
Vol 76 (2) ◽  
pp. 110-117 ◽  
Author(s):  
R Vianna-Jorge ◽  
C F Oliveira ◽  
Y Mounier ◽  
G Suarez-Kurtz
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Muscle Fibers ◽  
Fiber Types ◽  
Release Channel ◽  
Uridine Triphosphate ◽  
Skinned Muscle ◽  
Skeletal Muscle Fibers ◽  
Slow Type ◽  
Relationship Of

Chemically skinned human skeletal muscle fibers were used to study the effects of uridine triphosphate (UTP) on the tension-pCa relationship and on Ca2+ uptake and release by the sarcoplasmic reticulum (SR). Total replacement (2.5 mM) of adenosine triphosphate (ATP) with UTP (i) displaced the tension-pCa relationship to the left along the abcissae and increased maximum Ca2+-activated tension, both effects being larger in slow- than in fast-type fibers; (ii) markedly reduced Ca2+ uptake by the SR (evaluated by the caffeine-evoked tension) in both fiber types; (iii) had no effect on the rate of depletion of caffeine-sensitive Ca2+ stores during soaking in relaxing solutions; (iv) induced tension in slow- but not in fast-type fibers. The effects on the SR functional properties are consistent with the notion that UTP is a poor substitute for ATP as a substrate for the Ca ATPase pump and as an agonist of the ryanodine-sensitive Ca2+-release channel. The UTP-induced tension in human slow-type fibers is attributed to effect(s) of the nucleotide on the tension-pCa relationship of the contractile machinery. The present data reveal important differences between the effects of UTP on human versus rat muscle fibers.Key words: skinned muscle fiber, UTP-induced tension, tension-pCa relationship, sarcoplasmic reticulum, calcium transport.

Fasting Increases the Extent of Muscle Necrosis in the mdx Mouse

1996 ◽  
Vol 90 (6) ◽  
pp. 467-472 ◽  
Author(s):  
T. R. Helliwell ◽  
P. A. MacLennan ◽  
A. McArdle ◽  
R. H. T. Edwards ◽  
M. J. Jackson
Keyword(s):  
Mdx Mouse ◽  
Mdx Mice ◽  
Energy Status ◽  
Wild Type ◽  
Muscle Fibre Size ◽  
Fed State ◽  
Fibre Size ◽  
High Prevalence ◽  
Dystrophin Deficiency ◽  
Muscle Necrosis

1. The effects of fasting for 48 h were investigated in CS7BL/10 (wild type) and age-matched C57BL/10 dystrophin-deficient (mdx) mice. 2. Fasting resulted in an increased percentage of necrotic fibres in muscles from the hindlimb and lumbar regions of mdx mice. The percentage of necrotic fibres of forelimb and chest muscles of mdx mice was unaltered by fasting. In wild-type mice, very few necrotic fibres were observed after fasting. 3. The necrotic changes in fasted mdx muscle were not accompanied by altered energy status as evaluated by muscle ATP and phosphocreatine concentrations. 4. A significantly decreased rectal temperature was observed in mdx but not in wild-type mice after fasting. 5. Fasting would normally be expected to cause a reduction in muscle fibre size. The high prevalence of necrosis in fasted mdx mice is therefore an unusual response that may be related to disturbance of the mechanisms which, in the fed state, compensate for the dystrophin deficiency in these animals.

scholarly journals Expression of the glucose transporter GLUT4 in the muscular dystrophic mdx mouse

1993 ◽  
Vol 291 (1) ◽  
pp. 257-261 ◽  
Author(s):  
C Olichon-Berthe ◽  
N Gautier ◽  
E Van Obberghen ◽  
Y Le Marchand-Brustel
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membranes ◽  
Glucose Transporter ◽  
Mrna Level ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Mrna Levels ◽  
Skeletal Tissue ◽  
Muscle Tissues ◽  
And Control

Glucose transporter protein levels have been investigated in mdx and control (C57Bl/10) mice. Crude membrane fractions (microsomes plus plasma membranes) were prepared from skeletal muscle, heart, diaphragm and brain of 5-6-week-old and 6-7-month-old control and mdx mice. Using Western blot analysis with C-terminal-specific anti-peptide antibodies, we investigated the glucose transporters GLUT4 in the different muscle tissues and GLUT1 in brain. In skeletal tissue from the hindlegs, GLUT4 was increased by approximately 55% in mdx mice compared with control mice at both ages studied. In the diaphragm, the amount of GLUT4 protein was unchanged in young mdx mice, and was decreased by 37.4 +/- 4.7% in older mice compared with age-matched control mice. No difference was observed between mdx and control mice in the amounts of GLUT4 and GLUT1 in heart and brain preparations respectively. To determine whether the change in GLUT4 protein observed in the diaphragm and skeletal muscle of mdx mice was regulated through changes at the level of glucose transporter mRNA, Northern blot analyses were performed. In skeletal muscle, GLUT4 mRNA level per tissue was not different between the two groups of mice at both ages studied. In contrast, the decrease in the amount of GLUT4 protein observed in the diaphragm of 6-7-month-old mdx mice was accompanied by a decrease in the GLUT4 mRNA level. In conclusion, the levels of GLUT4 protein were modified in muscle tissues from mdx compared with control mice, and these modifications were different depending on the muscle involved and the age of the mice. An increase in the amount of GLUT4 protein in the skeletal muscle of mdx mice was not due to changes at the mRNA level. The diaphragms of 6-7-month-old mdx mice exhibited decreases in GLUT4 protein and mRNA levels that were not detected in young animals (5-6 weeks old).

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