These experiments explore the relationship between patterned impulse activity and contractile properties of skeletal muscles. Soleus (SOL) and extensor digitorum longus (EDL) muscles of adult rats were denervated and stimulated directly from 4 to 15 weeks with the same number of pulse trains at different intratrain pulse frequencies (1-500 Hz), with different numbers of pulse trains (864-4,320,...

Using a single, mechanically skinned fiber approach, we tested the hypothesis that denervation (0 to 50 days) of skeletal muscles that do not overlap in fiber type composition [extensor digitorum longus (EDL) and soleus (SOL) muscles of Long-Evans hooded rats] leads to development of different fiber phenotypes. Denervation (50 day) was accompanied by 1) a marked increase in the proportion of hy...

Hypoxia as a consequence of acute and chronic respiratory disease has been associated with muscle atrophy. This study investigated the sensitivity of oxidative and glycolytic muscles to hypoxia-induced muscle atrophy. Male mice were exposed to 8% normobaric oxygen for up to 21 days. Oxidative soleus and glycolytic extensor digitorum longus (EDL) muscles were isolated, weighed, and assayed for e...

The hypothesis of this study was that diabetes-induced desensitization of rat soleus (SOL) and extensor digitorum longus (EDL) to non-depolarizing muscle relaxants (NDMRs) depends on the stage of diabetes and on the kind of NDMRs. We tested the different magnitude of resistance to vecuronium, cisatracurium, and rocuronium at different stages of streptozotocin (STZ)-induced diabetes by the EDL s...

The skeletal muscle is classified into 2 types, slow oxidative or fast glycolytic muscle. For further characterization, we investigated the capillary architecture in slow and fast muscles. The rat soleus and extensor digitorum longus (EDL) muscles were used as representatives of slow and fast muscles, respectively. To investigate capillary density, sections of both types of muscle were stained ...

We examined the fiber profiles and the mRNA levels of peroxisome proliferator-activated receptors (PPARα and PPARδ/β) and of the PPARγ coactivator-1α (PGC-1α) in the plantaris muscles of 15-week-old control (WR), metabolic syndrome (CP), hypertensive (SHR), and type 2 diabetic (GK) rats. The deep regions in the muscles of SHR and GK rats exhibited lower percentages of high-oxidative type I and ...

Clenbuterol (CB) is one of the β2-adrenergic receptor agonists with powerful muscle anabolic and lipolytic effects, and is prohibited as a doping drug for athletes. However, it is one of the candidate countermeasures for aging-related diseases. Previously we reported that CB induced muscular hypertrophy, but inhibited the longitudinal growth of bones in young male rats. However, the mechanism o...

Neonatal sciatic nerve crush results in a sustained reduction of the mass of both extensor digitorum longus (EDL) and soleus (SOL) muscles in the rat. Type IIB fibers are selectively lost from EDL. We have investigated the effects of ciliary neurotrophic factor (CNTF) combined with neurotrophin (NT)-3 or NT-4 on muscle mass, as well as the number, cross-sectional area, and distribution of muscl...

This study examined dihydropyridine receptor (DHPR) gene expression in mouse skeletal muscles during physiological adaptations to disuse. Disuse was produced by three in vivo models-denervation, tenotomy, and immobilization-and DHPR alpha1s mRNA was measured by quantitative Northern blot. After 14-day simultaneous denervation of the soleus (Sol), tibialis anterior (TA), extensor digitorum longu...

It has long been suggested that in skeletal muscle, the ATP-sensitive K(+) channel (K(ATP)) channel is important in protecting energy levels and that abolishing its activity causes fiber damage and severely impairs function. The responses to a lack of K(ATP) channel activity vary between muscles and fibers, with the severity of the impairment being the highest in the most glycolytic muscle fibe...