The examination of muscle strength involves general functions as well as testing of specific muscles or muscle groups. Start studying Biochemistry of muscle metabolism. Sometimes muscle disorders can be part of a more diffuse disorder, e.g. Resting cell pH is set by processes of H+ efflux, dominated by the Na+/H+-antiporter, being the pH at which net H+ efflux is near-zero. Liver glycogen is the first and immediate source of glucose for the maintenance of blood glucose levels to meet the needs of the organism as a whole, especially of the brain and the RBCs. It may toughen muscles if the concomitant fast pH fall inactivates certain proteolytic enzymes. The situation is further complicated by the presence in smooth muscle tissue of a mixture of actin isotypes, including nonmuscle-type actins (Vandekerckhove and Weber, 1981), which are segregated in different compartments of the cell—in the contractile apparatus and in the cytoskeleton (North et al., 1994b). There are different types of skeletal muscles, which are broadly divided into white and red types. Butchers, and customers, may identify different cuts, but once the beef is off the bone and trimmed of fat it is difficult to distinguish lean beef from, for example, adults of different ages or from fast- and slow-cooled sides. While the lean and insulin-sensitive phenotype of adipocyte Atg7 KO mice is obesity resistant and appears to be metabolically “healthy”, the observation that the mice begin to die from unknown causes at eight weeks of life and exhibit ~40% mortality by 12 weeks of age cannot be overlooked, as it indicates that autophagy in adipose tissue is likely necessary for life. Efficiency quantifies the fraction of the energy consumed that appears as work. The metabolic basis for a change in muscle mass is an increase in net muscle protein balance (termed NBAL). Electrical stimulation (ES) of prerigor carcasses was patented 40 years ago to improve tenderness. Muscle, which contains two types of hexokinase (type I and type II), can phosphorylate fructose to fructose-6-phosphate (F6P) which is a direct glycolytic intermediate. Another technique employed recently by my colleagues and myself (Thomas et al., 1975a,b) utilizes a new variant of the electron spin resonance (ESR) technique developed by Hyde and his colleagues (Hyde and Dalton, 1972; Hyde and Thomas, 1973). Metabolic disorders often cause increased blood lactate after exercise. A full neurological examination should be performed to determine whether there is any other neurological abnormality. In terms of muscle protein metabolism, administration of testosterone to young volunteers eliminates the loss of amino acids from muscle in the fasted state . The glucose-6-phosphate released in the muscle tissue from glycogen can enter directly into glycolysis for energy production by the muscle. For the most part, exercising fish adhere to the classical scheme of substrate utilization during high-intensity exercise involving first CrP hydrolysis to power the first few tail flaps, then an activation of glycolysis with lactate accumulation. Beta oxidation of lipids is greatly increased in both WAT and BAT of adipocyte Atg7 KO mice indicating that the expanded mitochondrial population is functional and can contribute to whole body lipid utilization21, 73. Biochemistry for Sport and Exercise Metabolism addresses this problem by placing the primary emphasis on sport, and describing the relevant biochemistry within this context. In contrast, adipocyte autophagy KO mice do not exhibit increased lipid accumulation in non-adipose organs, likely owing to the expansion of BAT-like adipose tissue and increased lipid beta-oxidation providing increased body lipid clearance. Copyright © 2020 Elsevier B.V. or its licensors or contributors. Taken together, these findings implicate skeletal muscle autophagy in normal fed/fasting nutrient homeostasis and maintenance of skeletal muscle mass during aging, processes known to be important in the pathogenesis of insulin resistance and Type 2 diabetes. Autophagy is impaired, as expected, and histological examination reveals degenerative changes of vacuolization and central nucleation, with glycolytic and oxidative fibers equally affected. By continuing you agree to the use of cookies. Young bulls, and most cattle in the autumn, are more prone to stress and thus to produce DFD meat. This principle is probably also true of [Pi], which along with [ADP] defines ΔGATP (Eq. The estrogen-related receptor (ERR) family of nuclear receptors induces genes critical to both glucose and fatty acid metabolism and interacts with the PPARs to control cardiac metabolism. Decreases rapidly early postmortem. Biochemistry of muscle biopsy samples can show decreased activity of respiratory chain complexes. Selective spin labeling at the S-1 thiol groups with N-(1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl) was carried out. In cattle, prolonged stress premortem depletes muscle glycogen reserves and postmortem production of lactic acid from glycogen is inadequate to bring the physiological pH of muscle from 7 to 5.4–5.6, the normal level 48 h after slaughter. Chris J. Barclay, in Muscle and Exercise Physiology, 2019. The book covers the gross and detailed composition and structure of muscles and the relationship of the nervous system with the muscular system; muscle cell differentiation and growth; proteins of the thick filament; and the molecular structure and enzymatic activity of myosin. Figures are average ±SE μg collagen extracted from samples into medium (Goll DE, Hoekstra WG and Bray W (1964) Age associated changes in bovine muscle connective tissue. Rhythmic contraction and relaxation of glycerinated fibers of insect indirect flight muscle, in the presence of Mg2+, ATP, and Ca2+ are extensively described in Volume II, Chapter 10 (see Pringle, 1967). (5.9)) should, by hypothesis, be at a value appropriate to basal ATP demand, in accordance with the special case of Eq. Effect of Mg-ATP and Mg-ADP on ESR spectra of spin labeled myosin. HIF targets include a number of genes that are directly involved in upregulation of glucose metabolism [131]. S1, F to H) and calcium cycling (fig. Shin beef is cheapest of all. Autophagy is induced in skeletal muscle during fasting79, which serves to maintain circulating amino acids and glucose (by supplying gluconeogenic amino acids). There are increased rates of apoptosis in later stages of differentiation, and reduced numbers of WAT-like adipocytes in Atg5 total body KO mouse embryos74. It is also important to take a history of current drug exposure, as a variety of drugs have been associated with muscle disease, as discussed below. It has been well established that insect flight muscle possesses the most highly developed and specialized structure and function among the invertebrates (see Volume III, Chapter 7 by Pringle and this volume, Chapter 3 by Hoyle). First, the aP2-Cre promoter used in each study is active in development as early as embryonic day six. First, they reduce overall handling time because the prey does not need to be re-oriented after capture (which often involves repeatedly ejecting and recapturing the prey). Chapter 41: Haemostasis and Thrombosis. Rodger Laurent, in The Musculoskeletal System (Second Edition), 2010. This is in contrast to how mammals recover from intense exercise; they convert lactate into glucose in the liver and the muscle uses the subsequent glucose for glycogen resynthesis. Start studying Biochemistry - Chapter 9 - Carbohydrate Metabolism I (Practice Questions). This is revealed in increased motion of the spin label attached to the active center of the myosin head, specifically to one of the reactive sulfhydryl groups. By continuing you agree to the use of cookies. In order for muscles to contract, ATP must be available in the muscle fiber. Ultrastructural exam by TEM reveals accumulation of enlarged and dysmorphic mitochondria in muscle fibers of aging Atg7 KO muscle, suggesting impaired mitophagy26, 82. The primal cuts of the side differ slightly by country, but are based on convenient anatomical divisions, eating quality and costing. Solution for Problem 5.6. NBAL is the difference between MPS (muscle protein synthesis) and MPB (muscle protein breakdown). 7). Damage to the muscle cell membrane, e.g. In this chapter, the biochemical aspects of the structural proteins of myofibrils mainly of indirect flight muscle and their interaction with ATP will be described on the basis of the information available. S1, I to K) pathways. [37] showed that short-term rhGH therapy (for three consecutive days) in chronic HD patients resulted in a significant accrual of whole-body protein mass, primarily through an 18% increase in whole-body protein synthesis associated with a reduction essential amino acid muscle loss. Physiological biochemistry of the heat stressed cows is characterized by low-fat reserves derived NEFA (non-esterified fatty acids) response, despite high energy demands. Taken together these studies indicate that rhGH improves whole-body protein synthesis in children and adults with CKD in the short-term. Aerobic metabolism occurs within mitochondria of the muscle cells. An official transcript from each college or university attended 2. This is more frequent in children with mitochondrial disorders. There are numerous devices for accurately measuring muscle power, but size or cost precludes their use in the clinical setting. There are a few species (e.g., pike, walleye Sander vitreus, and rainbow trout Oncorhynchus mykiss) that preferentially attack prey at the tail or middle of the body, but even these fish usually rotate the prey to be swallowed headfirst. 9). Learn vocabulary, terms, and more with flashcards, games, and other study tools. Alternatively, it can be metabolized to pyruvate and then transaminated to alanine that is exported from the muscle to the liver, where it can be used as a substrate for gluconeogenesis. A. pH 1. Muscle metabolism is usually independent of cerebral metabolism, but some disorders induce combinations of muscle and cerebral impairments. Rather unsatisfactorily, we still (Kemp, 1994) do not know whether observed abnormalities in resting 31P MRS data in disease are quantitatively consistent with any version of Eq. Unlike hypokalemia, which does not alter the mental status, hyponatremia (sodium depletion) causes confusion, agitation, stupor, and seizures. Spectra of solutions containing S-1 labeled myosin, 14 mg/ml, 0.4 M KCl and 0.04 M Tris, pH 7.5 were recorded at room temperature. However, it is important to measure CoQ levels in muscle if histology shows lipid accumulation in addition to mitochondrial proliferation, because these findings can be present in treatable CoQ deficiency. In the insect the study of the ATP-actomyosin was initiated by Gilmour and Calaby (1953a) using locust muscle and extended by myself and my colleagues (Maruyama, 1954a,b; 1957a,b; 1958, 1959a; 1966; Maruyama and Allen, 1967; Maruyama et al., 1968; Kominz et al., 1962; Tsukamoto et al., 1966) in a number of species. Deficiency of a glycolytic or glycogenolytic enzyme leads to accumulation of glycogen and in some cases glycogen-related proteoglycans. Adipocyte Atg7 KO WAT depots are reduced in size and grossly abnormal in appearance and function: they have the appearance of BAT, including the presence of large numbers of mitochondria and multilocular small lipid droplets rather than a single large droplet. During recovery, pathways must be activated to resynthesize ATP, CrP, and glycogen in preparation for another possible bout of exercise. The clinical examination should carefully evaluate all muscle groups both proximally and distally, including the trunk and cervical muscles. ... Lastly, [ATP] is set as part of the wider biochemistry of the muscle cell, by the balance of adenine nucleotide synthesis and breakdown (Kemp et … Some species switch between alternate foraging modes when capturing and ingesting prey. Therefore, they are generally only used when prey that are small enough to be easily captured and swallowed whole are not available. Generally, biochemistry is not as important as histology for the diagnosis. 46,1972), smooth muscle biochemistry was only in its infancy. The ESR technique shows even less difference between the correlation times of S-1, HMM and myosin; this strongly suggests the conclusion, arrived at from fluorescence studies concerning segmental flexibility of the myosin molecule, of at least one hinge being located in the HMM portion at the junction of S-1 and the so-called subfragment-2 (S-2). A different disorder involving potassium metabolism is hypokalemic periodic paralysis, in which patients have dramatic attacks, lasting several hours to 2 days, of areflexic quadriparesis. Saturation transfer spectroscopy permits a more detailed investigation of the motion of the myosin heads when myosin molecules are organized into filaments or when myosin or its fragments are attached to actin. Inherited disorders of muscle metabolism (see E-Box 15-1) are characterized by reduced muscle cell energy production. Inherited lipid storage myopathies have not yet been described in animals, although dogs appear to have a predilection for development of neuromuscular weakness because of acquired lipid storage myopathy with concurrent reduction in skeletal muscle carnitine activity. Lower temperatures reduce tenderness pro rata. To elucidate the molecular mechanisms by which Nrf2 contributes … Mice with skeletal muscle-specific knockout of Atg726, 82 exhibit normal birth weight and growth until 40 days of age, at which point they exhibit reduced weight gain. Prior to the urea cycle, ammonium ions are produced from the breakdown of amino acids. One reason for this dilemma is that thin filaments from smooth muscle vary in their composition depending on the conditions employed for their isolation (see Small and Sobieszek, 1980; Nishida et al., 1990; Marston, 1991; Lehman, 1991), indicating that the actin-associated components are not tenaciously bound in a single, homogeneous complex. 5.20). At that point, the muscles must get their energy sources from elsewhere in the body, especially the liver, via the blood. Intimately connected with this fundamental problem of bioenergetics is the notion that certain movements within and between molecules making up the contractile apparatus underlie both muscle contraction and its regulation. However, until the advent of magnetic resonance spectroscopy, studies into the effects of lipid infiltration on muscle biochemistry were limited to an analysis of skeletal muscle biopsy specimens. This change in muscle biochemistry probably helps prepare these predators for the increased anaerobic performance required for pursuing larger fish. The more common of these are severe exercise, muscle trauma, drugs and hypothyroidism. ES causes muscular contractions, depleting the glycogen and other energy reserves in muscles, so preventing the cold shortening of slack muscles like LD. The first successful demonstration was obtained by Morales and his colleagues (Mendelson et al., 1973) in their studies of the depolarization of fluorescence emission by a fluorescent chromophore attached to the head portion of the myosin molecule. This contrasts with the time domain of fluorescence polarization and conventional electron spin resonance techniques, which are of the order of 10−7 sec. In contrast, members of the peroxisome proliferator-activated receptor (PPAR) family induce expression of genes promoting fatty acid oxidation. Insect flight muscles consist of myofibrils, sarcosomes (mitochondria), sarcoplasmic reticulum, nuclei, and sarcoplasmic sap (see Smith, 1966). However, there are other causes of an increased level of creatine kinase, which always need to be considered. This technique permits the calculation of the correlation time of the protein that carries the fluorescent dye. We use cookies to help provide and enhance our service and tailor content and ads. Adipocyte size, which is highly correlated with insulin resistance in most cohorts, was also highly correlated with Atg5 and Atg8 expression69. There are many different types of glycogen storage diseases, and their categorization is dependent on which enzyme is deficient. about 200 nsec. There are several important caveats for interpreting these data with regard to the pathophysiology of obesity and diabetes. Richards, in Encyclopedia of Fish Physiology, 2011. Other aspects of the resting muscle spectrum are of potential interest. 46,1972), smooth, FOOD ACQUISITION AND DIGESTION | Energetics of Foraging Decisions and Prey Handling, SWIMMING AND OTHER ACTIVITIES | Applied Aspects of Fish Swimming Performance, Visceral Fat Predicts Ectopic Fat Accumulation Mechanisms and Health Consequences, Nutrition in the Prevention and Treatment of Abdominal Obesity, . In rainbow trout, intense exercise elicited by chasing in a tank lasts between 1 and 5 min, and at the end of this exercise protocol the fish will have almost completely depleted muscle glycogen content, CrP and ATP content, as well as accumulate high levels of lactate and hydrogen ions, causing a severe acidosis. ), xPharm: The Comprehensive Pharmacology Reference, 3, 4 methylenedioxymethamphetamine (MDMA), Biochemistry of Smooth Muscle Contraction, -regulatory complexes in the contractile apparatus of cross-striated muscle (see, e.g., Cold Spring Harbor Symp. These modes of capture and consumption can allow a species to increase its dietary breadth, but are also energetically costly. Y. Wang, J.G. It has been hypothesized that the increased capacity of glucose transport in the skeletal muscle of trained subjects may facilitate the synthesis of intracellular triglycerides and at the same time increase the sensitivity to insulin. Electron microscopic examination of the fine structure of myofibrils has revealed that insect indirect flight muscle resembles in many ways rabbit striated muscle. This is cold shortening, and is confirmed by micrometry of the sarcomeres, units of the myofibrils. Low levels of ATP exist within the muscle fibers and can immediately provide energy for contraction. Pupim et al. Juvenile Atlantic salmon in streams are less willing to travel across prevailing currents to intercept drifting prey at increased flow velocities. Nevertheless, if one measures the overall efficiency of muscle (mechanical work/metabolic cost), muscle operates at only ~20% efficiency. 2. The current molecular biological mechanism of muscular contraction, based upon the interaction between adenosine triphosphate (ATP) and the contractile proteins, myosin and Factin, and the role of calcium ions through the sarcoplasmic reticulum and the calcium-receptive protein, troponin–tropomyosin complex, on one hand, and the electron microscopic and X-ray observations of the behavior of double arrays of filaments in myofibrils, on the other hand, are chiefly derived from a huge number of fruitful investigations on rabbit skeletal muscle (see Huxley, 1960, 1969; Ebashi and Endo, 1968; Ebashi and Nonomura, 1973). A few such disorders have been described in dogs, and a mitochondrial myopathy has been reported in one Arabian horse. There are other enzymes that are also elevated with muscle damage, but the creatine kinase has the best correlation with disease activity and is the best measure of muscle damage and response to treatment. Frequently there is a combined defect in the complexes because the underlying genetic defect of the mtDNA (large-scale deletions or tRNA mutations) affects several subunits of different complexes.65 If there is an isolated deficiency of one complex, a genetic defect in one subunit can be assumed. The existence of a close relationship between insulin resistance and lipid infiltration of the muscle seems to contradict the “metabolic athlete’s paradox” [120]. Lastly, [ATP] is set as part of the wider biochemistry of the muscle cell, by the balance of adenine nucleotide synthesis and breakdown (Kemp et al., 2014). Enquire about symptoms of connective tissue disease, e.g. The main intrinsic source of metabolic energy in a muscle fiber comes from the breakdown of glycogen, a carbohydrate polymer that yields the simple sugar glucose when it is enzymatically broken down into individual subunits. The interaction of ATP with myosin is clearly a key process in muscle contraction, and one of the outstanding problems of muscle biochemistry is to achieve an understanding of how this interaction results in the conversion of chemical into mechanical energy. It has been demonstrated that the lipid infiltration of muscle is associated with negative effects on metabolism and function. Thus an increase in MPS and/or a decrease in MPB are necessary for NBAL to increase, leading to accretion of muscle proteins. This review provides an overview of the relationship between muscle biochemistry and thermodynamics to illustrate the different definitions of efficiency and their values.