Creatine supplementation improves intracellular Ca2+ handling and survival in mdx skeletal muscle cells (original) (raw)
Related papers
Pharmacological control of cellular calcium handling in dystrophic skeletal muscle
Neuromuscular …, 2002
Duchenne muscular dystrophy arises due to the lack of the cytoskeletal protein dystrophin. In Duchenne muscular dystrophy muscle, the lack of dystrophin is accompanied by alterations in the dystrophin-glycoprotein complex. We and others have found that the absence of dystrophin in cells of the Duchenne muscular dystrophy animal model, the mdx mouse, leads to elevated Ca 21 influx and cytosolic Ca 21 concentrations when exposed to stress. We have also shown that a-methylprednisolone, the only drug used successfully in the therapy of Duchenne muscular dystrophy, and creatine lowered cytosolic Ca 21 levels in mdx myotubes. It is likely that chronic elevation of [Ca 21 ] in the cytosol in response to stress is an initiating event for apoptosis and/or necrosis in Duchenne muscular dystrophy or mdx muscle and that alterations in mitochondrial function and metabolism are involved. Other cellular signalling pathways (e.g. nitric oxide) might also be affected.
Effect of creatine supplementation on skeletal muscle ofmdx mice
Muscle & Nerve, 2004
Dystrophic mice (mdx) and their controls (C57/Bl10) were fed for 1 month with a diet with or without creatine (Cr) enrichment. Cr supplementation reduced mass (by 19%, P Ͻ 0.01) and mean fiber surface (by 25%, P Ͻ 0.05) of fast-twitch mdx muscles. In both strains, tetanic tension increased slightly (9.2%) without reaching statistical significance (P ϭ 0.08), and relaxation time increased by 16% (P Ͻ 0.001). However, Cr had no protective effect on the other hallmarks of dystrophy such as: susceptibility to eccentric contractions; large numbers of centrally nucleated fibers in tibialis anterior; and elevated total calcium content, which increased by 85% (P ϭ 0.008) in gastrocnemius mdx muscles. In conclusion, Cr does not cure the disease although it may be a positive intervention for improvement of muscle function.
Cell, 1997
We have blocked creatine kinase (CK)-mediated phosphocreatine (PCr) ^ ATP transphosphorylation in skel etal muscle by combining targeted mutations in the genes encoding mitochondrial and cytosolic CK in mice. Contrary to expectation, the PCr level was only marginally affected, but the compound was rendered metabolically inert. Mutant muscles in vivo showed significantly impaired tetanic force output, increased relaxation times, altered mitochondrial volume and lo cation, and conspicuous tubular aggregates of sarco plasmic reticulum membranes, as seen in myopathies with electrolyte disturbances. In depolarized myotubes cultured in vitro, CK absence influenced both the release and sequestration of Ca2^. Our data point to a direct link between the CK-PCr system and Ca2+flux regulation during the excitation and relaxation phases of muscle contraction.
Creatine monohydrate enhances strength and body composition in Duchenne muscular dystrophy
Neurology, 2004
Thirty boys with DD (50% were taking corticosteroids) completed a double-blind, randomized, cross-over trial with 4 months of CrM (about 0.10 g/kg/day), 6-week wash-out, and 4 months of placebo. Measurements were completed of pulmonary function, compound manual muscle and handgrip strength, functional tasks, activity of daily living, body composition, serum creatine kinase and γ-glutamyl transferase activity and creatinine, urinary markers of myofibrillar protein breakdown (
Neuromuscular Disorders, 2002
The mdx mouse serves as animal model for Duchenne muscular dystrophy. Energy status in muscles of mdx mice is impaired and we have demonstrated recently that the energy precursor creatine exerts beneficial effects on mdx skeletal muscle cells in culture. Here we show that feeding a creatine-enriched diet to new-born mdx mice strongly reduced the first wave of muscle necrosis four weeks after birth. Necrosis of the fast-twitch muscle extensor digitorum longus was inhibited by 63^14% (P , 0:0001) while necrosis of the slow-twitch soleus muscle was not significantly decreased. In addition, using chemically skinned muscle fibres, we found that mitochondrial respiration capacity was decreased by about 25% in mdx-derived fibres and that long-term creatine-feeding restored respiration to wild-type levels. These results provide evidence that creatine supplementation in mdx mice improves muscle health and may provide a scientific basis for its use as adjuvant therapy in Duchenne muscular dystrophy. q
Regulation of cytosolic calcium in skeletal muscle cells of the mdx mouse under conditions of stress
British Journal of Pharmacology, 1996
1 In Duchenne muscular dystrophy (DMD) dysregulation of cytosolic calcium appears to be involved in the degeneration of skeletal muscle fibres. Therefore, we have studied the regulation of the free cytosolic calcium concentration ([Ca2+]) under specific stress conditions in cultured myotubes isolated from the hind limbs of wild-type (C57BL10) and dystrophin-deficient mutant mdx mice. [Ca2+]c in the myotubes was estimated by the use of the Ca2'-sensitive fluorescent dye, fura-2. 2 Resting [Ca2+]c was similar in mdx and normal myotubes (35+9 nM and 38 + 11 nM, respectively).
Upregulation of the creatine synthetic pathway in skeletal muscles of mature mdx mice
Neuromuscular Disorders, 2007
Duchenne muscular dystrophy (DMD) is a fatal neuromuscular human disease caused by dystrophin deficiency. The mdx mouse lacks dystrophin protein, yet does not exhibit the debilitating DMD phenotype. Investigating compensatory mechanisms in the mdx mouse is important. This study targets two metabolic genes, guanidinoacetate methyltransferase (GAMT) and arginine:glycine amidinotransferase (AGAT) which are required for creatine synthesis. We show that GAMT and AGAT mRNA are up-regulated 5.4 and 1.9-fold respectively in adult mdx muscle compared to C57. In addition, GAMT protein expression is up-regulated at least 2.5-fold in five different muscles of mdx vs. control. Furthermore, we find GAMT immunoreactivity in 80% of mature mdx muscle fibers in addition to small regenerating fibers and rare revertants; while GAMT immunoreactivity is equal to background levels in all muscle fibers of mature C57 mice. The up-regulation of the creatine synthetic pathway may help maintain muscle creatine levels and limit cellular energy failure in leaky mdx skeletal muscles. These results may help better understand the mild phenotype of the mdx mouse and may offer new treatment horizons for DMD.
Beneficial effects of creatine supplementation in dystrophic patients
Muscle & Nerve, 2003
The effect of creatine (Cr) supplementation on muscle function and body composition of 12 boys with Duchenne muscular dystrophy and three with Becker dystrophy was evaluated by a randomized doubleblind cross-over study (3 g Cr or maltodextrin daily for 3 months, with wash-out period of 2 months). After placebo, no change was observed in maximal voluntary contraction (MVC) and resistance to fatigue, whereas total joint stiffness (TJS) was increased by ϳ25% (P Ͻ 0.05). The patients receiving Cr did not show any change in TJS, improved MVC by 15% (P ϭ 0.02), and almost doubled their resistance to fatigue (P Ͻ 0.001). In patients still independent of a wheelchair (n ϭ 5), bone mineral density increased by 3% (P Ͻ 0.05), and urinary excretion of collagen type I cross-linking Ntelopeptide declined to about one third (P Ͻ 0.001) after Cr. No adverse effect was observed. Thus, Cr may provide some symptomatic benefit in these patients.
2020
Key points • Creatine (Cr) plays an important role in muscle energy homeostasis as a substrate in the creatine kinase phosphoryl exchange reaction, but the consequences of creatine depletion are incompletely understood. • We assessed the morphological, metabolic and functional consequences of systemic creatine depletion on skeletal muscle in a mouse model with deficiency of an essential enzyme in the biosynthesis of creatine (AGAT −/− mice). • We show that Cr depletion leads to several metabolic abnormalities in muscle, including reduced ATP, increased inorganic phosphate levels and reduced activities of proton-pumping respiratory chain enzymes and an elevated glycolytic contribution in ischaemic circumstances. • The Cr-depleted muscle suffers from reduced grip strength, severe atrophy and abnormal mitochondrial structures, increased overall mitochondrial content and an increased number of lipid droplets. • Oral Cr administration led to rapid accumulation in skeletal muscle (faster ...
Calcium and the damage pathways in muscular dystrophy
Canadian Journal of Physiology and Pharmacology, 2010
Duchenne muscular dystrophy (DMD) is a severe muscle-wasting disease caused by the absence of the cytoskeletal protein dystrophin. Experiments on the mdx mouse, a model of DMD, have shown that mdx muscles are particularly susceptible to stretch-induced damage. In this review, we discuss evidence showing that a series of stretched contractions of mdx muscle fibres causes a prolonged increase in resting intracellular calcium concentration ([Ca 2+ ] i ). The rise in [Ca 2+ ] i is caused by Ca 2+ entry through a class of stretch-activated channels (SAC NSC ) for which one candidate gene is TRPC1. We review the evidence for activation of SAC NSC in muscle by reactive oxygen species (ROS) and suggest that stretch-induced ROS production is part of the pathway that triggers increased channel activity. When the TRPC1 gene was transfected into C2 myoblasts, expression occurred throughout the cell. Only when the TRPC1 gene was coexpressed with caveolin-3 did the TRPC1 protein express in the membrane. When TRPC1 was expressed in the membrane, it could be activated by ROS to produce Ca 2+ entry and this entry was inhibited by PP2, an inhibitor of src kinase. These results suggest that stretched contractions activate ROS production, which activates src kinase. Activity of this kinase causes opening of SAC NSC and allows Ca 2+ entry. This pathway appears to be a significant cause of muscle damage in DMD.