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Oxygen Transport
Published in James N. Cobley, Gareth W. Davison, Oxidative Eustress in Exercise Physiology, 2022
P.N. Chatzinikolaou, N.V. Margaritelis, A.N. Chatzinikolaou, V. Paschalis, A.A. Theodorou, I.S. Vrabas, A. Kyparos, M.G. Nikolaidis
Many researchers believe that all oxygen is used in mitochondrial respiration to produce ATP (Hill et al., 2012; Pittman, 2016). This notion is even more widely spread among exercise physiologists because skeletal muscle cells are rich in mitochondria and the energy-centric point of view prevails. However, it is now known that certain enzymes consume oxygen (e.g., oxygenases) and are localized mostly in the cytoplasm and not mitochondria (Romero et al., 2018). The most well-characterized enzymes consuming oxygen for purposes other than respiration are NADPH oxidases, NO synthases, xanthine oxidase, cyclooxygenases and lipoxygenases (Wagner, Venkataraman and Buettner, 2011). These enzymes have been found to be expressed in skeletal muscle in diverse cellular locations (Gomez-Cabrera et al., 2005; McConell et al., 2012; Henríquez-Olguin et al., 2019). As their activity increases during exercise, they become important consumers of oxygen in cases of increased contractile activity.
Introduction: Background Material
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
An important subset of living cells is excitable cells, which, when stimulated by an adequate stimulus of appropriate strength, undergo specific changes in the ionic permeabilities of their cell membranes. These permeability changes cause variations in the voltage across the cell membranes of excitable cells, which can result in a characteristic electric signal known as the action potential (AP) or nerve impulse (Chapter 3). The most important excitable animal cells are: (i) sensory cells, or receptors, which respond directly to environmental stimuli such as light, touch, taste, and smell, (ii) nerve cells, or neurons, whose primary function is the processing and transmission of information, and (iii) muscle cells, whose primary function is the development of a mechanical force of contraction. Neurons are discussed in Chapter 7, muscle cells and their receptors in Chapter 9.
The cell and tissues
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
ATP is required to fuel: Energy production itself. It is necessary to initiate glycolysis and fatty acid oxidation.Active transport of electrolytes across the plasma membrane, e.g., the Na+/K+ pump that restores the resting potential of the heart’s pacemaker cells.The amplification of the second messenger systems in cells. This process involves small amounts of signalling molecules (for example, water soluble hormones and neurotransmitters) attaching to the surface of the cell and initiating a process involving a number of membrane and intracellular proteins, that amplify the message to ensure that there is a sufficient response within the cell. This means that a relatively weak signal can produce a significant cellular action. The amino acid endocrines, such as antidiuretic hormone, function in this way.Contraction of skeletal, cardiac and smooth muscle cells.Phosphorylation of molecules to enable and enhance reactions in the cell.
A review of surgical management of progressive myogenic ptosis
Published in Orbit, 2023
Royce B. Park, Sruti S. Akella, Vinay K. Aakalu
Oculopharyngeal muscular dystrophy (OPMD) is a slowly progressive disease involving symmetric blepharoptosis, dysphagia, and proximal muscle weakness.3 It is inherited in an autosomal dominant pattern and its onset is insidious, typically manifesting during the fifth or sixth decade of life.3 French Canadians (Quebec), Hispanic New Mexicans, and Israeli Bukhara Jewish populations are most prevalently affected by OPMD.13 The condition is diagnosed through molecular genetic testing and manifests as a myopathy affecting skeletal muscle cells.38 The levator palpebrae superioris and pharyngeal muscles are often most severely impaired, but the disease can also involve other extraocular muscles and limb muscle groups.38 Patients will compensate for progression of ptosis with contraction of the frontalis muscle and “backward head tilt.”38 Meanwhile, the orbicularis oculi muscle and Bell’s phenomenon are fairly well-preserved in OPMD patients.3 Surgical techniques described include blepharoplasty, levator advancement, frontalis sling, and combined aponeurosis-Muller muscle advancement.12
The ultrastructure of muscle fibers and satellite cells in experimental autoimmune encephalomyelitis after treatment with transcranial magnetic stimulation
Published in Ultrastructural Pathology, 2022
María Angeles Peña-Toledo, Evelio Luque, Manuel LaTorre, Ignacio Jimena, Fernando Leiva-Cepas, Ignacio Ruz-Caracuel, Eduardo Agüera, J. Peña-Amaro, Isaac Tunez
Transmission electron microscopy (TEM) is a very useful tool for studying muscle fibers in the EAE model to accurately evaluate the effects of tested MS treatments. In addition, TEM is the best technique for studying the population of satellite cells by using morphological criteria.4 It is well known that these cells, which are associated with muscle fibers, are responsible for muscle growth and regeneration phenomena and, consequently, always play an essential role in the response of muscle cells to any therapeutic strategy used to treat neuromuscular disorders.11 Indeed, stimulation of the population of satellite cells is one of the factors that favors recovery from muscle atrophy.12 In this regard, it has been shown that satellite cells from MS patients maintained their proliferative and differentiation capacity.13 Therefore, this population represents a possible therapeutic target for the treatment of the muscular problems present in MS.
Impact of methionine restriction on muscle aerobic metabolism and hypertrophy in young and old mice on an obesogenic diet
Published in Growth Factors, 2022
Anandini Swaminathan, Leonardo Cesanelli, Tomas Venckunas, Hans Degens
Mitochondria play a vital role in cellular ATP production, necessary for muscle contraction and viability of muscle cells. The mitochondrial dysfunction during ageing may impinge on proteostasis and result in a loss of muscle mass and function (Bellanti, Lo Buglio, and Vendemiale 2021), and may occur as a result of increased reactive oxidative species (ROS) production and lowered antioxidant defences (Miquel et al. 1980; McCormick and Vasilaki 2018). The low-grade systemic inflammation induced by obesity and old age, combined with deteriorated mitochondrial function, is especially relevant to older obese adults who have higher levels of muscular fat infiltration (Choi et al. 2016). Calorie restriction and exercise have been shown to delay the ageing- and obesity-associated impairment of mitochondrial function (Bhatti, Bhatti, and Reddy 2017; Ruetenik and Barrientos 2015). Similarly, it has been observed that while there was an absence of mitochondrial biogenesis, there was an increase in mitochondrial oxidative capacity in skeletal muscle of young-adult rats fed a MR diet (Perrone et al. 2010). Whether this increase in mitochondrial capacity in skeletal muscle after MR extends to old age and obesity is yet to be elucidated.