Aging is associated with an increase in insulin resistance in skeletal muscle, yet the underlying mechanism is not well established. We hypothesize that with aging, a chronic increase in stress kinase activation, coupled with a decrease in oxidative capacity, leads to insulin resistance in skeletal muscle. In aged (24 mo old) and young (3 mo old) Fischer 344 rats, 2-deoxyglucose uptake and insu...

To investigate whether changes in blood flow contribute to the insulin resistance in denervated muscles, basal and insulin-stimulated 2-deoxy-d-glucose (2-DG) uptake in vivo and blood flow were measured in soleus (slow twitch), plantaris (fast twitch), and gastrocnemius (fast twitch) muscles at 1 and 3 days after a right hindlimb denervation in the rat. Muscles of the contralateral sham hindlim...

The ability of muscles from Glut 4-null mice to take up and metabolize glucose has been studied in the isolated white EDL and red soleus muscles. In EDL muscles from male or female Glut 4-null mice, basal deoxyglucose uptake was lower than in control muscles and was not stimulated by insulin. In parallel, glycogen synthesis and content were decreased. Soleus muscles from male Glut 4-null mice t...

Miniature end plate potential (mepp) frequency in innervated extensor muscle is significantly higher than in soleus muscle. 9 days after nerve crush mepps of low amplitude and prolonged duration reappeared at a frequency of 2% of control and were similar to normal muscles after 35 days. Membrane potential began to increase 9-10 days after nerve crush and at 30 days was similar to controls. The ...

Contractile and histochemical properties of rat soleus muscle were studied bilaterally after 2 or 4 weeks of denervation (DEN), which eliminates activity and non-activity-related influences, and chronic application of tetrodotoxin (TTX) to the motor nerve, which produces a completely inactive innervated muscle. After 2 or 4 weeks of disuse, the percentages of slow twitch oxidative fibers in bot...

BACKGROUND Estrogens are associated with the loss of skeletal muscle strength in women with age. Ovarian hormone removal by ovariectomy in mice leads to a loss of muscle strength, which is reversed with 17beta-estradiol replacement. Aging is also associated with an increase in antioxidant stress, and estrogens can improve antioxidant status via their interaction with estrogen receptors (ER) to ...

objective(s):this study examined whether conjugated linoleic acid (cla) supplementation affects insulin sensitivity and peroxisome proliferator-activated receptor gamma (ppar-γ) and glucose transporter type 4 (glut-4) protein expressions in the skeletal muscles of rats during endurance exercise. materials and methods:sprague-dawley male rats were randomly divided into hs (high-fat diet (hfd) se...

Post-tetanic potentiation of muscle contraction strength (PTP) occurs in cat soleus and gastrocnemius muscles. However, the mechanisms of potentiation are different in these two muscles. Soleus PTP is predominantly a neural event. The application of a high frequency stimulus to the soleus nerve regularly causes each subsequent response to a single stimulus to become repetitive. This post-tetani...

Doxorubicin (DOX) is a potent antitumor agent used in cancer treatment. Unfortunately, DOX can induce myopathy in both cardiac and skeletal muscle, which limits its clinical use. Importantly, exercise training has been shown to protect against DOX-mediated cardiac and skeletal muscle myopathy. However, the mechanisms responsible for this exercise-induced muscle protection remain elusive. These ...

This investigation examined the effect of mechanical loading state on focal adhesion kinase (FAK), paxillin, and serum response factor (SRF) in rat skeletal muscle. We found that FAK concentration and tyrosine phosphorylation, paxillin concentration, and SRF concentration are all lower in the lesser load-bearing fast-twitch plantaris and gastrocnemius muscles compared with the greater load-bear...