• Journal of Animal Science and Technology
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• 제66권2호
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• pp.251-265
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• 2024

Meat derived from skeletal muscles of animals is a highly nutritious type of food, and different meat types differ in nutritional, sensory, and quality properties. This study was conducted to compare the results of previous studies on the muscle fiber characteristics of major porcine skeletal muscles to the end of providing basic data for understanding differences in physicochemical and nutritional properties between different porcine muscle types (or meat cuts). Specifically, the muscle fiber characteristics between 19 major porcine skeletal muscles were compared. The muscle fibers that constitute porcine skeletal muscle can be classified into several types based on their contractile and metabolic characteristics. In addition, the muscle fiber characteristics, including size, composition, and density, of each muscle type were investigated and a technology based on these muscle fiber characteristics for improving meat quality or preventing quality deterioration was briefly discussed. This comparative review revealed that differences in muscle fiber characteristics are primarily responsible for the differences in quality between pork cuts (muscle types) and also suggested that data on muscle fiber characteristics can be used to develop optimal meat storage and packaging technologies for each meat cut (or muscle type).

• Animal Bioscience
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• 제36권2_spc호
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• pp.374-384
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• 2023

Skeletal muscle metabolism regulates homeostatic balance in animals. The metabolic impact persists even after farm animal skeletal muscle is converted to edible meat through postmortem rigor mortis and aging. Muscle metabolites resulting from animal growth and postmortem storage have a significant impact on meat quality, including flavor and color. Metabolomics studies of postmortem muscle aging have identified metabolisms that contain signatures inherent to muscle properties and the altered metabolites by physiological adaptation, with glycolysis as the pivotal metabolism in postmortem aging. Metabolomics has also played a role in mining relevant postmortem metabolisms and pathways, such as the citrate cycle and mitochondrial metabolism. This leads to a deeper understanding of the mechanisms underlying the generation of key compounds that are associated with meat quality. Genetic background, feeding strategy, and muscle type primarily determine skeletal muscle properties in live animals and affect post-mortem muscle metabolism. With comprehensive metabolite detection, metabolomics is also beneficial for exploring biomarker candidates that could be useful to monitor meat production and predict the quality traits. The present review focuses on advances in farm animal muscle metabolomics, especially postmortem muscle metabolism associated with genetic factors and muscle type.

• 한국전문물리치료학회지
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• 제5권1호
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• pp.63-78
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• 1998

The decrease of muscle power and muscle size between twenties and seventies was about 30% and 40% respectively. The loss of muscle mass by aging resulted in the decrease of muscle power. The loss of muscle mass was due to the decrease of number of Type I fiber and Type II fiber and size of each muscle fiber. The aging skeletal muscle didn't show the loss of glycolysis capacity but showed 20% decrease of the oxidative enzymes and muscle vascularization. The vigorous endurance exercise training with graded intensity played a role in the vascular proliferation, increase of activity of oxidative enzymes and improvement of $VO_2$ max. The graded resistance exercise also played a role in the muscle hypertrophy and increase of muscle power, if it performed with adequate intensity and period. The exercise adaptation of aging skeletal muscle prevented it from sarcopenia, provided the activity of daily living with great effect and provided the aging related disease, that is Type II diabetes mellitus, arteriosclerosis, hypertension, osteoporosis and obesity, with great effect.

• 대한의생명과학회지
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• 제17권4호
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• pp.283-289
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• 2011

Our previous study demonstrated that the Korean traditional medicine Gyeongshingangjeehwan (GGEx) activates AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor ${\alpha}$ ($PPAR{\alpha}$) critical for fatty acid oxidation in skeletal muscle and C2C12 skeletal muscle cells. Thus, we examined whether GGEx can reduce lipid accumulation in these cells and tissues. After obese and type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats were treated with GGEx, we studied the effects of GGEx on skeletal muscle lipid accumulation. The effects of GGEx and/or the AMPK inhibitor compound C on lipid accumulation and expression of AMPK and $PPAR{\alpha}$ were measured in C2C12 skeletal muscle cells. Compared with lean Long-Evans Tokushima Otsuka rats, obese OLETF rats had increased triglyceride droplets. However, administration of GGEx to OLETF rats for 8 weeks significantly decreased triglyceride droplets in skeletal muscle. Consistent with the $in$ $vivo$ data, GGEx inhibited lipid accumulation, the degree of which was comparable to Wy14,643, the potent activator of $PPAR{\alpha}$. GGEx also increased skeletal muscle mRNA levels of AMPK${\alpha}1$, AMPK${\alpha}2$, and $PPAR{\alpha}$. However, compound C inhibited these effects in C2C12 cells. These results suggest that GGEx suppresses skeletal muscle lipid accumulation and this process may be mediated by AMPK and $PPAR{\alpha}$ activation.

• BMB Reports
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• 제39권4호
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• pp.457-463
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• 2006

Insulin resistance is commonly observed in patients prior to the development of type 2 diabetes and may predict the onset of the disease. We tested the hypothesis that impairment in insulin stimulated glucose-disposal in insulin resistant patients would be reflected in the gene expression profile of skeletal muscle. We performed gene expression profiling on skeletal muscle of insulin resistant and insulin sensitive subjects using microarrays. Microarray analysis of 19,000 genes in skeletal muscle did not display a significant difference between insulin resistant and insulin sensitive muscle. This was confirmed with real-time PCR. Our results suggest that insulin resistance is not reflected by changes in the gene expression profile in skeletal muscle.

• International Journal of Stem Cells
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• 제15권3호
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• pp.283-290
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• 2022

Background and Objectives: Difficulties often encountered in separating and purifying active muscle satellite cells (MSCs) from skeletal muscle tissues have limited the supply of cells for muscle therapy and artificial meat production. Here, we report an effective isolation protocol to economically and conveniently retrieve active MSCs from skeletal muscle tissues in mice. Methods and Results: We optimized an enzyme-based tissue digestion protocol for isolating skeletal muscle-derived primary cell population having a large number of active MSCs and described a method of differential plating (DP) for improving purity of active MSCs from skeletal muscle-derived primary cell population. Then, the age of the mouse appropriate to the isolation of a large number of active MSCs was elucidated. The best isolation yield of active MSCs from mouse skeletal muscle tissues was induced by the application of DP method to the primary cell population harvested from skeletal muscle tissues of 2-week-old mice digested in 0.2% (w/v) collagenase type II for 30 min at 37℃ and then in 0.1% (w/v) pronase for 5 min at 37℃. Conclusions: The protocol we developed not only facilitates the isolation of MSCs but also maximizes the retrieval of active MSCs. Our expectation is that this protocol will contribute to the development of original technologies essential for muscle therapy and artificial meat industrialization in the future.

• 한국가시화정보학회지
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• 제20권2호
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• pp.70-77
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• 2022

Skeletal muscle tissues feature cellular heterogeneity, including differentiated myofibers, myoblasts, and satellite cells. Thanks to the presence of undifferentiated myoblasts and satellite cells, skeletal muscle tissues can self-regenerate after injury. In skeletal muscle regeneration, the collective motions among these cell types must play a significant role, but little is known about the dynamic collective behavior during the regeneration. In this study, we constructed in vitro platform to visualize the migration behavior of skeletal muscle cells in specific conditions that mimic the biochemical environment of injured skeletal muscles. We then visualized the spatiotemporal distribution of stresses arising from the differential collectiveness in the cellular clusters under different conditions. From these analyses, we identified that the heterogeneous population of muscle cells exhibited distinct collective migration patterns in the injury-mimicking condition, suggesting selective activation of a specific cell type by the biochemical cues from the injured skeletal muscles.

• Asian-Australasian Journal of Animal Sciences
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• 제19권10호
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• pp.1496-1502
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• 2006

Skeletal muscle contains slow and fast twitch fibers. These skeletal muscle fibers express type I and type II myosin, respectively, and these myosin isoenzymes have different ATPase activity. The aim of this study was to investigate protein profiles of bovine skeletal muscles by proteomic analysis. Fifty seven spots of distinct proteins were excised and characterized. The expression of sixteen spots was differed in longissimus dorsi muscle with a minimal 2-fold change compared to biceps femoris muscle. The majority of differentially expressed proteins belonged to metabolic regulation-related proteins such as glyceraldehyde 3-phosphate dehydrogenase, triosephosphate isomerase and carbonic anhydrase 3. The real time-PCR assay confirmed an increase or induction of specific genes: RGS12TS isoform, GAPDH, triosephosphate isomerase and carbonic anhydrase. These results suggest that the expression of metabolic proteins is under a specific control system in different bovine skeletal muscle. These observations could have significant implications for understanding the physiological regulation of bovine skeletal muscles.

• 대한정형도수물리치료학회지
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• 제13권1호
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• pp.58-66
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• 2007

The purpose of this study is to understand the structure and biomechanics of the skeletal muscle. The skeletal muscle takes 40 to 45% of the whole body. Stable posture requires a balance of muscle. However, when the muscle strength is unbalanced, movement initiates. The power generated by the muscle is a primary means to adjust the equilibrium of posture and movement. The structural unit of the skeletal muscle is a long cylindrical type muscle fiber which contains hundreds of nucleus. The thickness of muscle fiber is about $10-100{\mu}m$, and its length is about 1-50cm. Muscle fiber is composed of myofibril that is covered with plasma membrane which is called sarcolemma. In understanding the movement of human body, it is important to comprehend the movement of bone and joint and the tension of muscle. Understanding the structure and biomechanics of muscle also provides basic information on clinical treatment of patients.

• 농업과학연구
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• 제45권1호
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• pp.50-57
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• 2018

Meat comes from the skeletal muscles of farm animals, such as pigs, chickens, and cows. Skeletal muscles are composed of many muscle fibers. Muscle fibers are categorized into three types, fiber type I, IIA, and IIB, based on their contractile speed and metabolic properties. Different muscle fiber types have different biochemical, physiological, and biophysical characteristics. Especially, the characteristics of muscle fiber type I and IIB are opposite to each other. Muscle fiber type I has a relatively strong oxidative metabolic trait and a higher content of lipids. In contrast to fiber type I, muscle fiber type IIB has a strong glycolytic metabolic trait and a relatively lower content of lipids and a higher content of glycogen. Muscle fiber type IIA has intermediate properties between fiber type I and IIB. Thus, muscles with different fiber type compositions exhibit different ante- and post-mortem muscle characteristics. In particular, the different metabolic traits of muscles due to the different compositions of the fiber types strongly affect the biochemical and physiological processes during the conversion of muscle to meat and subsequently influence the quality of the meat. Therefore, understating muscle metabolism and muscle fiber characteristics is very important when discussing the traits of meat quality. This review is an overview on basic muscle metabolism, muscle fiber characteristics, and their influence on meat quality and finally provides a comprehensive understanding about the fundamental traits of muscles and meat quality.