Michael gundill steroides

Previous strength training with or without the use of anabolic steroids facilitates subsequent re-acquisition of muscle mass even after long intervening periods of inactivity. Based on in vivo and ex vivo microscopy we here propose a cellular memory mechanism residing in the muscle cells. Female mice were treated with testosterone propionate for 14 days, inducing a 66% increase in the number of myonuclei and a 77% increase in fibre cross-sectional area. Three weeks after removing the drug, fibre size was decreased to the same level as in sham treated animals, but the number of nuclei remained elevated for at least 3 months (> 10% of the mouse lifespan). At this time, when the myonuclei-rich muscles were exposed to overload-exercise for 6 days, the fibre cross-sectional area increased by 31% while control muscles did not grow significantly. We suggest that the lasting, elevated number of myonuclei constitutes a cellular memory facilitating subsequent muscle overload hypertrophy. Our findings might have consequences for the exclusion time of doping offenders. Since the ability to generate new myonuclei is impaired in the elderly our data also invites speculation that it might be beneficial to perform strength training when young in order to benefit in senescence.

Dans les présents travaux, nous avons étudié l’effet de la troxérutine (TRX) sur la fatigue musculaire et l’expression des gènes Bcl-2 et Bax dans le tissu hépatique de rat. Nous avons réparti aléatoirement 40 rats Wistar mâles dans les quatre groupes suivants : témoin et administration de TRX à 75 (TRX75), 150 (TRX150) et 300 mg/kg par jour (TRX300). Les groupes TRX et placebo ont reçu pendant 7 jours de la TRX et de l’eau, respectivement. Le 7e jour, tous les animaux ont été euthanasiés immédiatement après un test de nage menant à l’épuisement, et nous avons mesuré plusieurs paramètres biochimiques liés à la fatigue et à l’expression des gènes Bcl-2 et Bax dans le tissu hépatique. Nos résultats ont montré que dans le groupe TRX300, le temps de nage écoulé avant l’épuisement était 1,2 fois plus élevé que dans le groupe témoin (résultats statistiquement significatifs : P < 0,001).

Skeletal muscle stem cells (satellite cells; SC) represent the primary
cell population responsible for muscle regeneration/repair. SC content
and activation has been show to increase in response to muscle
damaging exercise. However, non-satellite cell progenitors, under experimental
conditions in animals, have been identified to form skeletal
muscle when the SC population is compromised. PW1+ interstitial
cells (PIC) have also been shown, experimentally, to contribute to
muscle repair in animals. This cell population, however, has never
been identified in humans. We sought to examine the changes in both
PIC and SC content following a single bout of eccentric exercise. Ten
sedentary males (24±3 years of age; mean±SEM) were recruited. Percutaneous
muscle biopsies from the vastus lateralis muscle were taken
prior to a bout of eccentric exercise (Pre), and 6h, 24h, and 72 h
post-exercise. Muscle fiber size, SC and PIC content were determined
via immunofluorescent microscopy. mRNA expression was assessed
by RT-PCR. The number of SC increased from Pre (± Pax7+cells/
100 fibers) to 72h post-exercise (± Pax7+cells/100 fibers, p

Michael gundill steroides

michael gundill steroides


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