Search results for "skeletal muscle"

Long lasting high fat feeding increases the capillary density in the skeletal muscle of mice

2010

O2Transport in Skeletal Muscle: Development of Concepts and Current State

1994

When comparing oxygen consumption rates(V O2) of various organs — as shown in Fig. 1 —skeletal muscle is exceptional in two respects: Its consumption rate attains the second largest absolute value of all organs and may vary between rest (0.2 mlO 2.100g-1’• min -1 ) and maximum performance (16 m1O 2.100g-1 • min -1 for electrical stimulation) by a factor of 80, thus covering a range that is by far larger than in any other tissue. In order to understand muscle O 2 transport one has to identify transport mechanisms and evaluate their importance towards bringing about the observed high O 2 fluxes and allowing for their enormous variability.

Exercise and hormesis: activation of cellular antioxidant signaling pathway.

2006

Contraction-induced production of reactive oxygen species (ROS) has been shown to cause oxidative stress to skeletal muscle. As an adaptive response, muscle antioxidant defense systems are upregulated after heavy exercise. Nuclear factor (NF) kappaB and mitogen-activated protein kinases (MAPKs) are the major oxidative stress-sensitive signal transduction pathways in mammalian tissues. Activation of NF-kappaB signaling cascade has been shown to enhance the gene expression of important enzymes, such as mitochondrial superoxide dismutase (MnSOD) and inducible nitric oxide synthase (iNOS). MAPK activations are involved in a variety of cellular functions including growth, proliferation, and adap…

Role of nuclear factor κB and mitogen-activated protein kinase signaling in exercise-induced antioxidant enzyme adaptation

2007

Activation of nuclear factor (NF) κB and mitogen-activated protein kinase (MAPK) pathways in skeletal muscle has been shown to enhance the gene expression of several enzymes that play an important role in maintaining oxidant–antioxidant homeostasis, such as mitochondrial superoxide dismutase (MnSOD) and inducible nitric oxide synthase (iNOS). While an acute bout of exercise activates NFκB and MAPK signaling and upregulates MnSOD and iNOS, administration of chemical agents that suppress reactive oxygen species (ROS) production can cause attenuation of exercise-induced MnSOD and iNOS expression. Thus, ROS generation during exercise may have duel effects: the infliction of oxidative stress an…

Molecular signaling in muscle is affected by the specificity of resistance exercise protocol

2010

Mammalian target of rapamycin and mitogen-activated protein kinase (MAPK) signaling pathways have been highlighted as important for muscle adaptations and thus, they may distinguish adaptations to different exercises. Typically, resistance exercise designed for muscle hypertrophy has moderate intensity (60-80% of one repetition maximum, 1 RM) while one prioritizing maximal strength with minor hypertrophy has a higher intensity (≥90% of 1 RM). Eight untrained men (28.4 ± 3.7 years) conducted two different bilateral leg press exercise protocols: hypertrophic (5 × 10 RM) and pure maximal strength (15 × 1 RM) in a counterbalanced, cross-over design with 1 week between exercises. Vastus laterali…

Bimodal Recovery Pattern in Human Skeletal Muscle Induced by Exhaustive Stretch-Shortening Cycle Exercise:

2007

Introduction/Purpose: Recovery of force and stretch reflex from exhaustive stretch-shortening cycle (SSC) exercise is usually bimodal, characterized as immediate exercise-induced performance reduction, with its quick recovery followed by a longer-lasting reduction in performance. A clear parallel exists between the respective changes in performance, neural activation, and metabolic or structural exercise-induced changes. This implies the existence of potential coupling between muscle failure and the induced neural adjustments that take place along its recovery. The present study was designed to explore the evidence of this coupling more thoroughly. Methods: H- and stretch reflexes were meas…

Rats bred for low aerobic capacity become promptly fatigued and have slow metabolic recovery after stimulated, maximal muscle contractions.

2012

AIM. Muscular fatigue is a complex phenomenon affected by muscle fiber type and several metabolic and ionic changes within myocytes. Mitochondria are the main determinants of muscle oxidative capacity which is also one determinant of muscle fatigability. By measuring the concentrations of intracellular stores of high-energy phosphates it is possible to estimate the energy production efficiency and metabolic recovery of the muscle. Low intrinsic aerobic capacity is known to be associated with reduced mitochondrial function. Whether low intrinsic aerobic capacity also results in slower metabolic recovery of skeletal muscle is not known. Here we studied the influence of intrinsic aerobic capac…

The healthy Nordic diet predicts muscle strength 10 years later in old women, but not old men

2017

Background a number of nutrients have been found to be associated with better muscle strength and mass; however, the role of the whole diet on muscle strength and mass remains still unknown. Objective to examine whether the healthy Nordic diet predicts muscle strength, and mass 10 years later among men and women. Methods about 1,072 participants belong to the Helsinki Birth Cohort Study, born 1934–44. Diet was assessed with a validated food-frequency questionnaire during 2001–04. The Nordic diet score (NDS) was calculated. The score included Nordic fruits, vegetables, cereals, ratio of polyunsaturated to saturated fatty acids, low-fat milk, fish, red meat, total fat and alcohol. Higher scor…

Systemic blockade of ACVR2B ligands attenuates muscle wasting in ischemic heart failure without compromising cardiac function

2020

Signaling through activin receptors regulates skeletal muscle mass and activin receptor 2B (ACVR2B) ligands are also suggested to participate in myocardial infarction (MI) pathology in the heart. In this study, we determined the effect of systemic blockade of ACVR2B ligands on cardiac function in experimental MI, and defined its efficacy to revert muscle wasting in ischemic heart failure (HF). Mice were treated with soluble ACVR2B decoy receptor (ACVR2B-Fc) to study its effect on post-MI cardiac remodeling and on later HF. Cardiac function was determined with echocardiography, and myocardium analyzed with histological and biochemical methods for hypertrophy and fibrosis. Pharmacological blo…

Active acetylcholine receptors prevent the atrophy of skeletal muscles and favor reinnervation

2020

Denervation of skeletal muscles induces severe muscle atrophy, which is preceded by cellular alterations such as increased plasma membrane permeability, reduced resting membrane potential and accelerated protein catabolism. The factors that induce these changes remain unknown. Conversely, functional recovery following denervation depends on successful reinnervation. Here, we show that activation of nicotinic acetylcholine receptors (nAChRs) by quantal release of acetylcholine (ACh) from motoneurons is sufficient to prevent changes induced by denervation. Using in vitro assays, ACh and non-hydrolysable ACh analogs repressed the expression of connexin43 and connexin45 hemichannels, which prom…