Enzymatic activity from the muscle-specific isoform of phosphoglycerate mutase (PGAM-M) is higher within glycolytic skeletal muscles than in oxidative muscles. The hypothesis that PGAM-M is regulated pretranslationally among muscles of the hindlimb was tested using enzymatic assays, Western blots, and Northern blots. We further investigated the regulatory level(s) at which PGAM-M gene expressio...

The purposes of this study were to determine the effects of ovarian hormone removal on force-generating capacities and contractile proteins in soleus and extensor digitorum longus (EDL) muscles of mature female mice. Six-month-old female C57BL/6 mice were randomly assigned to either an ovariectomized (OVX; n = 13) or a sham-operated (sham; n = 13) group. In vitro contractile function of soleus ...

β-Hydroxy-β-methylbutyrate (HMB) is a leucine metabolite shown to reduce protein catabolism in disease states and promote skeletal muscle hypertrophy in response to loading exercise. In this study, we evaluated the efficacy of HMB to reduce muscle wasting and promote muscle recovery following disuse in aged animals. Fisher 344×Brown Norway rats, 34 mo of age, were randomly assigned to receive e...

The protein deacetylase sirtuin 1 (SIRT1) and activate peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) pathway drives the muscular fiber-type switching, and can directly regulate the biophysiological functions of skeletal muscle. To investigate whether 12-week swimming exercise training modulates the SIRT1/PGC-1α pathway associated proteins expression in rats of different a...

The effects of food deprivation on protein turnover in rat soleus and extensor digitorum longus (EDL) were investigated. Muscles were removed from fed or fasted growing rats, and protein synthesis and breakdown were measured during incubation in vitro. Rates of synthesis and degradation were higher in the dark soleus than in the pale EDL. One day after food removal protein synthesis and RNA con...

The Achilles tendon (AT) consists of distinct fascicle bundles arising from the gastrocnemius and soleus muscles that intertwine and twist before inserting onto the calcaneus [1]. Current musculoskeletal models simplify this architecture by representing the gastrocnemius and soleus as independent muscle-tendon actuators [2], which may be an appropriate assumption if the fascicles freely slide r...

In order to study muscle gene expression during ageing, we examined both protein and total cellular RNA from Wistar F455 rat soleus and extensor digitorum longus (EDL) muscles at a variety of chronological ages. We found no evidence of the reappearance of the fast protein isoform of myosin light chain 1 [MLC1] in the slow soleus muscle during ageing previously reported by Syrovy and Gutmann, Pf...

Denervation induces skeletal muscle atrophy, which primarily impairs oxidative slow twitch fibers. The underlying mechanism of this phenomenon, however, remains to be addressed. We hypothesize that denervation-induced fiber-specific atrophy may result from the distinct activities of different signaling pathways that are involved in protein synthesis and degradation in fast- and slow-twitch fibe...

Twelve rabbits were cast-immobilized for 4 weeks during which either 10- or 50-Hz stimulation was applied transcutaneously to the anterior compartment muscles. After the treatment period, tibialis anterior and soleus muscle contractile and histochemical properties were measured. Tibialis anterior stimulation at either 10 or 50 Hz had significantly different effects on the ipsilateral, unstimula...