To elucidate the possible role of the mitochondrial uncoupling protein (UCP)-3 in skeletal muscle as a regulator of adaptive thermogenesis and energy balance, we examined the modulation by cold exposure (5°C) of UCP-3 and glucose transporter isoform GLUT-4 mRNAs in male Sprague-Dawley rats. In skeletal muscle, UCP-3 and GLUT-4 mRNAs increased two- to threefold between 6 and 24 h of cold exposur...

The effects of phosphate depletion (PD) of 4, 8, and 12 weeks on skeletal muscle energy metabolism were studied in rats fed a phosphate deficiency diet and compared with rats pairfed with a normal phosphate diet. Skeletal muscle biopsy specimens were examined for energy production, transport, and utilization. The results show that already by 4 weeks of PD, the concentration of inorganic phospho...

Submitochondrial particles obtained from skeletal muscle are open membrane fragments which show energy coupling yet cannot sustain transmembrane ion gradients. An energy-linked decrease in fluorescence emission of the fluorescent probe quinacrine is observed with skeletal muscle particles which is enhanced by the anion SCN-. This is essentially the same reaction observed with beef heart submito...

Introduction. Regulation of liver insulin receptors has been extensively studied in various physiopathological states such as diabetes, obesity and starvation (Czech, 1985). In contrast, muscle insulin receptors have only been poorly studied despite the fact that muscle is a major target organ for insulin. Some works demonstrated that skeletal muscle insulin receptors, like liver insulin recept...

Background Many athletes restrict energy intake to achieve a certain body mass category, aesthetic benefits or to attain a better force-to-mass ratio to improve performance. This rapid weight loss, also known as “weight cutting”, usually involves several-day fasting until a target weight is achieved. However, fasting is a well-known stimulus to activate two major protein degradation pathways, t...

This investigation used a model of increased skeletal muscle contractile activity to evaluate whether the adenylate cyclase-adenosine 3',5'-cyclic monophosphate (cAMP) pathway and/or the high-energy phosphate state of the muscle might be temporally related to the contraction-induced increase in skeletal muscle GLUT-4 protein concentration. Plantaris and gastrocnemius muscles of Sprague-Dawley r...

OBJECTIVE Increased signal transducer and activator of transcription 3 (STAT3) signaling has been implicated in the development of skeletal muscle insulin resistance, though its contribution, in vivo, remains to be fully defined. Therefore, the aim of this study was to determine whether knockout of skeletal muscle STAT3 would prevent high-fat diet (HFD)-induced insulin resistance. METHODS We ...

The physiological flux of oxygen is extreme in exercising skeletal muscle. Hypoxia is thus a critical parameter in muscle function, influencing production of ATP, utilization of energy-producing substrates, and manufacture of exhaustion-inducing metabolites. Glycolysis is the central source of anaerobic energy in animals, and this metabolic pathway is regulated under low-oxygen conditions by th...

Usually mathematicians use Hodgkin-Huxley model or FitzHug-Nagumo model to simulate action potentials of skeletal muscle fibers. These models are electrically excitable, but skeletal muscle fibers are stimulated chemically. To investigate skeletal muscle fibers we use a model with six ordinary differential equations. This dynamical system is sensitive to initial value of some variables so it is...