Numerical Simulation of a Physiological Mathematical Model of Energy Consumption in a Sarcomere / Simulación Numérica de un Modelo Matemático Fisiológico de Consumo de Energía en un Sarcómero

ABSTRACT The paradigm of biological systems provides a framework to quantify the behavior of biological processes. Mathematical modeling is one of the analytical tools of biological systems used to reproduce the variables of a system for prediction. This article presents the analysis of muscular contraction, the physiological process responsible of generating force in skeletal muscle, from the point of view of mathematical modeling. The aim is to provide numerical evidences about the force generated by the sarcomere, and the energy required to produce such a force. The proposed scheme includes a model to activate the contractile cycle, based on the action potential that reaches the neuromuscular junction, the calcium release into the sarcoplasm, the contraction response, and the quantification of the energy that the sarcomere requires to perform mechanical work. The results shows that the proposed scheme is acceptable because it reproduces experimental data of force, velocity, and energy reported in the literature. The results of the proposed scheme are encouraging to scale the model at the muscle or muscle group level, in such a way that the quantification of energy can be an alternative to the indirect estimation methods of energy consumption that currently exist.

Beef quality of Nellore steers fed dried or rehydrated and ensiled corn or sorghum grains / Calidad de la carne de Ganado Nelore alimentado con grano de maíz o sorgo seco o rehidratado y ensilado / Qualidade de carne de bovinos Nelore alimentados com grãos de milho ou sorgo seco ou reidratado e ensilado

Abstract Background: Rehydration of grains, such as corn and sorghum, is used to increase nutrient absorption. However, the effect of this practice on meat quality is poorly understood. Objective: To evaluate the effects of type of grain and processing on the meat quality of Nellore steers in a feedlot. Methods: Twenty-four non-castrated Nellore steers (270 ± 53 kg initial body weight) were distributed in a completely randomized 2×2 factorial design, with six replicates. The first factor was cereal type (corn or sorghum), and the second was the grain processing (dry or rehydrated and ensiled). The diets were composed of 30% corn silage and 70% concentrate. Sixty days before the beginning of the experiment, corn and sorghum grains were rehydrated and ensiled. The animals were slaughtered after 140 days of confinement. Meat quality analyses were determined in samples of fresh and aged meat (7 days) from the Longissimus lumborum muscle. Results: no difference between treatments was observed for carcass pH and L* (lightness), a* (redness), and b* (yellowness) values, shear force, thawing and cooking losses, and chemical composition of meat (p>0.05). The b* (yellowness) value of subcutaneous fat was higher in steers fed corn, regardless of grain processing (p=0.03). Sarcomere length was higher in aged meat of steers fed sorghum, regardless of processing method (p=0.01). Conclusions: the grain processing method does not affect beef quality; however, grain type can affect subcutaneous fat color and sarcomere length of aged beef.

Resumen Antecedentes: La rehidratación de granos, tales como maíz y sorgo, se usa para aprovechar mejor sus nutrientes. Sin embargo, es poco conocido el efecto de esta práctica sobre la calidad de la carne. Objetivo: Evaluar los efectos del tipo de cereal y su procesamiento sobre la calidad de carne de toretes Nelore en confinamiento. Métodos: Veinticuatro novillos Nelore enteros con un peso promedio inicial de 270 ± 53 kg, se distribuyeron en un diseño factorial 2×2 completamente aleatorizado (n=6). El primer factor fue el tipo de cereal (maíz o sorgo) y el segundo fue su procesamiento (seco o rehidratado y ensilado). Las dietas estuvieron compuestas por 28,44% de ensilaje de maíz y 71,56% de concentrado. Sesenta días antes de iniciar el experimento, los granos de maíz y sorgo se rehidrataron y ensilaron. Los animales se sacrificaron después de 140 días de confinamiento. La calidad de la carne se determinó en muestras de carne fresca y madurada (7 días) obtenidas del músculo Longissimus lumborum. Resultados: No hubo diferencias entre tratamientos para el pH de las canales, ni para los valores de color (L* "luminosidad", a* "intensidad de rojo" y b* "intensidad de amarillo"), fuerza de corte, composición química, o pérdidas de agua por descongelamiento o cocción (p>0,05). El valor de b* de la grasa subcutánea fue mayor en los novillos alimentados con maíz, independientemente del tipo de procesamiento (p=0,03). La longitud de sarcómero fue más alto en la carne madurada de novillos alimentados con sorgo, sin importar el método de procesamiento (p=0,01). Conclusiones: El método de procesamiento del grano no afecta la calidad de la carne; sin embargo, el tipo de cereal afecta el color de la grasa subcutánea y la longitud del sarcómero de la carne madurada.

Resumo Antecedentes: A reidratação de grãos, como milho e sorgo, tem sido usada para aumentar a utilização de seus nutrientes. Contudo, o efeito dessa prática na qualidade da carne é pouco compreendido. Objetivo: Avaliar os efeitos do tipo de grão de cereais e seu processamento sobre a qualidade da carne de bovinos confinados. Métodos: Vinte e quatro bovinos Nelore não castrados, com peso corporal médio inicial de 270 ± 53 kg foram distribuídos em delineamento inteiramente casualizado, fatorial 2×2, com seis repetições. O primeiro fator foi o tipo de grão de cereal no concentrado (milho ou sorgo), e o segundo foi o processamento destes grãos (seco ou reidratado e ensilado). As dietas foram compostas por 28,44% de silagem de milho e 71,56% de concentrado. Sessenta dias antes do início do experimento, os grãos de milho e sorgo foram reidratados e ensilados. Os animais foram abatidos após 140 dias de confinamento. As análises de qualidade da carne foram determinadas em amostras não maturadas e maturadas (7 dias) obtidas do músculo Longissimus lumborum. Resultados: Não houve diferenças significativas (p>0,05) entre os tratamentos para pH da carcaça e L* (luminosidade), a* (intensidade de vermelho), b* (intensidade de amarelo), força de cisalhamento, perdas por descongelamento, perdas por cocção, perdas totais e composição química da carne. O valor de b* da gordura subcutânea foi maior (p=0,03) em bovinos alimentados com dietas contendo grãos de milho, independentemente do tipo de processamento. O comprimento de sarcômero foi maior na carne maturada de novilhos alimentados com sorgo, independente do método de processamento (p=0,01). Conclusões: O método de processamento dos grãos não afetou a qualidade da carne bovina, no entanto, a cor da gordura subcutânea e o comprimento de sarcômero da carne maturada foram afetados pelo tipo de grão.

Sarcomere gene mutations and dilated cardiomyopathy / 国际儿科学杂志

Dilated cardiomyopathy (DCM) is the most common type of childhood myocardial disease in the clinic.It is mainly characterized by left ventricular or biventricular enlargement and myocardial contractile dysfunction,often accompanied by various arrhythmias.DCM is insidious and has a high rate of sudden death.At present,there is no alternative option to heart transplantation,thus DCM seriously threatens the life and health of children.With the rapid development of bioinformatics,second-generation sequencing and data mining are widely used in DCM diagnosis and treatment.Many sarcomere gene mutations such as MYH7,TNNT2,TTN,have attracted wide attention during the development of DCM.In this paper,the research results of sarcomere gene mutation and DCM in recent years are summarized,and the function of the corresponding gene and its effect on the heart are discussed.This review describes the specific mechanism of DCM gene mutation leading to DCM,which provides a reference for future DCM precision medicine.

Sarcomere structure: the importance of desmin protein in muscle atrophy / Estructura de sarcómera: la importancia de proteína desmina en atrofia muscular

Knowing the ultrastructure of skeletal muscle is critical to understand how it works under normal situation and the disorders caused by extreme or pathological conditions. Sarcomere is the basic structural unit of striated muscle tissue. An important element of sarcomere architecture are the intermediate filaments, including the desmin protein. Desmin protein contributes to maintenance of cell integrity, efficient transmission of force and mechanochemical signaling within the myocyte. Because of this, desmin protein has constantly been a focus of research that investigates its alterations associated to damage and muscle atrophy under different conditions. The purpose of the following literature review is to describe the basic concepts of muscle ultrastructure, emphasizing the desmin protein role under conditions of muscle disuse atrophy and aging.

Conocer la ultraestructura del músculo esquelético es crítico para entender cómo trabaja bajo situaciones normales y en desórdenes causados por condiciones extremas o patológicas. La sarcómera es la unidad de estructura básica del tejido muscular estriado. Elementos importantes en la arquitectura de la sarcómera son los filamentos intermedios, incluyendo la proteína desmina. La proteína desmina contribuye en mantener la integridad celular, la transmisión eficiente de fuerza y la señalización mecanoquímica dentro del miocito. Debido a lo anterior, la proteína desmina ha sido constante foco de investigación en trabajos que estudian sus alteraciones asociadas a daño y atrofia muscular bajo diferentes condiciones. El propósito de la siguiente revisión de la literatura es describir los conceptos básicos de la ultraestructura muscular, enfatizando en el rol de la proteína desmina bajo condiciones de atrofia muscular por desuso y envejecimiento.

Myosin-binding Protein C Compound Heterozygous Variant Effect on the Phenotypic Expression of Hypertrophic Cardiomyopathy / Mutação em Hetrozigose Composta no Gene da Proteína C Ligante de Miosina e sua Expressão Fenotípica na Cardiomiopatia Hipertrófica

Abstract Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic disease caused by mutations in genes encoding sarcomere proteins. It is the major cause of sudden cardiac death in young high-level athletes. Studies have demonstrated a poorer prognosis when associated with specific mutations. The association between HCM genotype and phenotype has been the subject of several studies since the discovery of the genetic nature of the disease. This study shows the effect of a MYBPC3 compound variant on the phenotypic HCM expression. A family in which a young man had a clinical diagnosis of HCM underwent clinical and genetic investigations. The coding regions of the MYH7, MYBPC3 and TNNT2 genes were sequenced and analyzed. The proband present a malignant manifestation of the disease, and is the only one to express HCM in his family. The genetic analysis through direct sequencing of the three main genes related to this disease identified a compound heterozygous variant (p.E542Q and p.D610H) in MYBPC3. A family analysis indicated that the p.E542Q and p.D610H alleles have paternal and maternal origin, respectively. No family member carrier of one of the variant alleles manifested clinical signs of HCM. We suggest that the MYBPC3-biallelic heterozygous expression of p.E542Q and p.D610H may cause the severe disease phenotype seen in the proband.

Resumo A cardiomiopatia hipertrófica (CMH) é uma doença autossômica dominante causada por mutações em genes que codificam as proteínas dos sarcômeros. É a principal causa de morte súbita cardíaca em atletas jovens de alto nível. Estudos têm demonstrado um pior prognóstico associado a mutações específicas. A associação entre genótipo e fenótipo em CMH tem sido objeto de diversos estudos desde a descoberta da origem genética dessa doença. Este trabalho apresenta o efeito de uma mutação composta em MYBPC3 na expressão fenotípica da CMH. Uma família na qual um jovem tem o diagnóstico clínico de CMH foi submetida à investigação clínica e genética. As regiões codificadoras dos genes MYH7, MYBPC3 e TNNT2 foram sequenciadas e analisadas. O probando apresenta uma manifestação maligna da doença e é o único em sua família a desenvolver CMH. A análise genética pelo sequenciamento direto dos três principais genes relacionados à essa doença identificou uma variante em heterozigose composta (p.E542Q e p.D610H) em MYBPC3. A análise da família mostrou que os alelos p.E542Q e p.D610H tem origem paterna e materna, respectivamente. Nenhum familiar portador de um dos alelos variantes manifestou sinais clínicos de CMH. Sugerimos que a expressão heterozigótica bialélica de p.E542Q e p.D610H pode ser responsável pelo fenótipo severo da doença encontrada no probando.

Diverse Muscular Adaptation between Aged and Young Groups in a Rabbit Model of Tibial Lengthening / The Japanese Journal of Rehabilitation Medicine

Skeletal muscles are overstretched following limb lengthening procedures. Muscles can adapt to this lengthening by adding new sarcomeres in series. Recent developments in limb lengthening provide adult patients more opportunities to undergo limb lengthening procedures. The purpose of this study was to clarify the difference in muscle adaptation between adult and young groups using a rabbit model of limb lengthening. Five mature (10-43 month old) and 6 immature (3-4 month old) white rabbits underwent tibial osteotomy. After a 1-week lag phase, tibial lengthening was applied at a rate of 1.4 mm/day for 2 weeks. Animals were euthanized after the completion of lengthening. Both hindlimbs were immersed in buffered formalin with the ankle and knee at a right angle. Muscle belly length, muscle fiber bundle length and sarcomere length were measured, and sarcomere number and internal tendon length were calculated in five representative muscles around the lengthened segment. Muscle belly length increased in all the lengthened muscles compared with the corresponding contralateral muscles regardless the group. Aponeurosis length increased significantly in one muscle for the adult group and three muscles for the young group. Sarcomere length tended to be longer or was significantly longer in the lengthened muscles. Serial sarcomere number significantly increased in 3 lengthened muscles in the adult group with a more conspicuous increase in the amount, while this occurred in 2 muscles in the young group with only a tiny increase. The predominant processes of skeletal muscle adaptation to the limb lengthening are sarcomere number addition in muscle fibers for the adult group and elongation of internal tendon for the young group.

Ultrastructure and compression elasticity of sarcomere in different activated states using atomic force microscopy / 医用生物力学

Objective To construct a system for studying the ultrastructure and mechanical properties of insect flight muscle fiber in different activated states so as to carry out cardiac biomechanics study in physiological environment, and further promote understanding of the relationship between cardiac structure, mechanical properties and physiological function, and provide more clues for the basic and clinical research on cardiac diseases. Methods The ultrastructure of insect flight muscle fibrils in rigor, relaxed and activated state was investigated using the tapping mode of atomic force microscopy (AFM), and the elasticity of muscle fibers in different physiological states was studied using the nanoindentation. Results Sarcomere lengths of insect flight muscle fiber in rigor, relaxed and activated state were (2.10±0.05), (3.10±0.10), (2.50±0.15) μm (2 mmol/L Ca2+), (2.60±0.25) μm (5 mmol/L Ca2+) and (2.55±0.15) μm (10 mmol/L Ca2+), respectively, while the A-band length maintained at 1.50 μm and I-band changed from 0.7~1.6 μm. Mechanical test found that the elasticity of different bands or lines in the same physiological state varied in the order of Z-line>M-line>overlap>I-band. Conclusions Critical Ca2+ concentration for muscle fiber activation was 5 mmol/L, and sarcomere length distributions were in line with the relative slip theory and structure model, and AFM was the potential tool for the high resolution study on ultrastructure and mechanical properties of the muscle fibers.

Tendon Transfer Increases Passive Tension of the Entire Muscle, Fiber Bundle and Single Fiber / The Japanese Journal of Rehabilitation Medicine

Skeletal muscle is known to be set at an over-stretched length in clinical tendon transfer. Such chronic stretching of skeletal muscle increases the serial sarcomere number required for muscle adaptation. Passive tension of the muscle must be affected during the adaptation. Thus, the objective of this study was to clarify the origin of increased passive tension after stretched tendon transfer in an animal model. The distal tendon of the extensor digitorum of the second toe was transposed to the extensor retinaculum at 3.7 mm of muscle sarcomere length. The contralateral muscle served as control. Muscle passive length-tension curves were measured at 1 week and 4 weeks after the transfer to the bilateral muscles. After functional measurements were taken, the muscles were dissected into fiber bundles and single muscle fibers to measure their passive mechanical properties with a micro force transducer. Passive tension was increased in the transferred muscle with a steeper inclination and leftward shift of muscle length-tension curve. Elastic modulus of the transferred fiber bundle increased at both time points, while those of the transferred single fibers increased only at 1 week. Results of the study suggest that the transferred muscle increased passive tension mainly due to proliferation of extracellular connective tissue within the muscle. Increased passive tension was a characteristic feature for the transferred muscle, which may ultimately represent a target for therapeutic intervention to optimize muscle function.

Princípios fisiológicos do aquecimento e alongamento muscular na atividade esportiva[revisão] / Physiological principles of warm-up and muscle stretching on sports activities

O objetivo deste estudo foi revisar a importância do aquecimento e alongamento muscular na prática esportiva, destacando seus principais efeitos fisiológicos e benefícios, haja vista que o presente assunto tem causado muita dúvida aos atletas profissionais ou amadores bem como em profissionais da área da saúde na realização e prescrição, respectivamente, da prática do aquecimento e alongamento muscular. Foram utilizados 52 textos, entre artigos da base de dados PubMed e livros publicados de 1978 a 2008. Do total, 18 (34,62 por cento) estavam em português e 34 (65,38 por cento) em inglês. Resultados mostraram que o aquecimento tem por principal objetivo prevenir lesões devido à sua gama de efeitos fisiológicos. A realização do alongamento no término do gesto esportivo tem por finalidade evitar o encurtamento muscular, ou se realizado diariamente e por um longo período, favorecer o aumento do número de sarcômeros e, consequentemente, proporcionar um ganho de flexibilidade.

The purpose of this study was to analyze the importance of warming-up and muscle stretching on sports practice, highlighting its main physiological effects and benefits, since the present issue has caused much doubt to professional or amateur athletes as well as to professionals of the health field on designing and prescribing warming-up and muscle stretching, respectively. For this purpose, 52 texts, including articles from PubMed database and books published from 1978 to 2008, were used. From de total, 18 (34.62 percent) were written in Portuguese and 34 (65.38 percent) in English. Results showed that warming-up has the main objective to prevent injuries due to its multitude of physiological effects. The performance of stretching in the end of the sportive gesture has the purpose to prevent muscular shortening, or if carried out daily and for a long period, to provide increase in the number of sarcomeres and consequently to provide flexibility gain.

Análise longitudinal de músculos sóleos, de ratos, submetidos a alongamento passivo com uso prévio de ultrassom terapêutico / Longitudinal analysis of soleus muscles of rats submitted to passive stretching with previous use of therapeutic ultrasound

O alongamento muscular é muito difundido entre atletas e pessoas envolvidas em atividades físicas, além de procedimento rotineiro em clínicas de fisioterapia, principalmente visando o aumento na flexibilidade. O ultrassom terapêutico possui ações térmicas e atérmicas, o que gera possibilidades de aumento de extensibilidade tecidual e metabolismo celular, e pode auxiliar nos efeitos anabólicos do alongamento estático. O objetivo deste estudo foi analisar os efeitos do alongamento passivo estático em músculo sóleo esquerdo (MSE) de ratos, associado ao uso do ultrassom terapêutico, sobre alterações longitudinais do tecido muscular. Foram utilizados 42 ratos Wistar, divididos em grupos tratados com ultrassom terapêutico com doses térmicas e não, e subsequente alongamento estático em três séries de 30s, além de grupos apenas tratados com ultrassom ou alongados, durante 15 dias de tratamento. Foram comparadas as variações encontradas entre o MSE e o MSD de cada grupo. As variáveis foram: comprimento muscular, estimativa de sarcômeros em série na fibra e ao longo do músculo, e comprimento de sarcômeros. Os resultados das variáveis analisadas apontaram alterações no comprimento muscular de repouso nos grupos em que foi associado ultrassom terapêutico, em dose térmica, ao alongamento estático, mas para as outras variáveis analisadas não houve diferenças significativas. Conclui-se que o alongamento passivo estático e o uso associado do ultrassom terapêutico, de forma térmica, produziram apenas aumento no comprimento muscular em repouso.

Muscular stretching is much diffused among athletes and people involved in physical activities, besides being a routine procedure in physiotherapy clinics, mainly aiming at flexibility increase. The therapeutic ultrasound possesses thermal and non-thermal effects, which generate possibilities of tissue extensibility and cellular metabolism increase and can aid in static stretching anabolic effects. The aim of this study was to analyze the static passive stretching effects in left soleus muscle (LSM) of rats, associated to the therapeutic ultrasound use on muscular tissue longitudinal alterations. Forty-two Wistar rats, divided in therapeutic ultrasound treated groups, with thermal and non-thermal doses, and subsequent static stretching in 3 sets of 30 s, besides groups just treated with ultrasound or stretched, for 15 days were used. The variations found between LSM and RSM of each group were compared. The variables were: muscular length, serial sarcomere estimation in the fiber and along the muscle, and sarcomere length. The analyzed variables results showed alterations in rest muscular length in the groups with therapeutic ultrasound in thermal dose associated to static stretching. However, there were not significant differences for the other analyzed variables. It is concluded that static passive stretching associated to therapeutic ultrasound in thermal dose just produced increase in rest muscular length.

Efeitos da corrida em esteira em músculos sóleos de ratos encurtados por imobilização / Effects of running on treadmill in soleus muscles of rats shortened by immobilization

O objetivo deste trabalho foi verificar as adaptações de peso e comprimento do músculo sóleo de ratos Wistar machos, além da estimativa do total de sarcômeros em série e comprimento médio dos sarcômeros, quando submetidos a um processo de remobilização em esteira. Foram utilizados 18 ratos (Wistar), divididos em três grupos: GC - músculo sóleo esquerdo (MSE) imobilizado e remobilizado solto; G10 - MSE imobilizado e remobilizado em velocidade de 10m/min; e G12 (n = 6) - MSE imobilizado e remobilizado em velocidade de 12m/min. Os resultados mostraram as seguintes variações, peso muscular: GC -22,35 por cento (p = 0,0089), G10 -12,52 por cento (p = 0,0623), G12 -12,07 por cento, (p = 0,0004); comprimento muscular: GC -5,47 por cento (p = 0,0120), G10 -3,31 por cento (p = 0,2868), G12 0,41 por cento (p = 0,8987); estimativa de sarcômeros em série: GC -15,42 por cento (p = 0,0047), G10 -10,87 por cento (p = 0,0193), G12 -4,97 (p = 0,2409); comprimento de sarcômeros GC 11,16 por cento (p = 0,0142), G10 9,31 por cento (p = 0,1270), G12 5,58 por cento (p = 0,1327). Conclui-se que G12 obteve maior eficácia após o período de imobilização, pois apresentou maior semelhança com o membro não imobilizado.

The aim of this work was to compare weight and length adaptations of the soleus muscle of male Wistar rats as well as estimation of the total number of serial sarcomere and mean sarcomere length, when they are submitted to remobilization on treadmill. 18 Wistar male rats were used and divided in the three following groups: CG - left soleus (LS) muscle immobilized and remobilized free in the cage; G10 - LS muscle immobilized and remobilized in speed of 10 m/min on treadmill; and G12 - LS muscle immobilized and remobilized in speed of 12 m/min. The right muscles (RS) of each animal were used for comparison. The results showed the following variations, muscular weigh: CG -22.35 percent (p = 0.0089), G10 -12.52 percent (p = 0.0623), G12 -12.07 percent, (p = 0.0004); muscle length: CG -5.47 percent (p = 0.0120), G10 -3.31 percent (p = 0.2868), G12 0.41 percent (p = 0.8987); estimation of number of serial sarcomere: CG -15.42 percent (p = 0.0047), G10 -10.87 percent (p = 0.0193), G12 -4.97 (p = 0.2409); sarcomere length: CG 11.16 percent, (p = 0.0142), G10 9.31 percent (p = 0.1270), G12 5.58 percent (p = 0.1327). It was concluded that G12 presented the best effectiveness after immobilization period since it presented greater similarity with the non-immobilized soleus.

Efeitos da remobilização em duas semanas com natação sobre o músculo sóleo de ratos submetidos à imobilização / Effects of remobilization in two weeks of swimming on the soleus muscle of rats submitted to immobilization

Uma importante questão para a reabilitação é como proteger o músculo esquelético dos efeitos da imobilização, pois, o músculo é o mais mutável dentre os tecidos biológicos e responde às demandas normais ou alteradas com adaptações morfológicas e funcionais. O objetivo deste artigo foi verificar o efeito de duas diferentes intensidades de carga de natação sobre a morfologia do músculo sóleo, e se são eficazes para reverter o processo de atrofia causado pela imobilização durante o período de 15 dias. Foram utilizados 10 ratos, com idade de 10±2 semanas, divididos em 2 grupos: G1 (imobilização/natação sem peso) e G2 (imobilização/natação com sobrecarga de 10 por cento do peso corporal). Dentro das variáveis analisadas ao comparar o membro esquerdo (submetido à imobilização) com o direito (não submetido) foram observados: para peso muscular em G1=-20,55 por cento (p=0,0344) e G2= -17,02 por cento (p=0,0053); comprimento muscular em G1= -10,66 por cento (p=0,0011) e G2= -6,55 por cento (p=0,1016); estimativa de sarcômeros em série no músculo para G1= -14,18 por cento (p=0,0101) e G2= -10,99 por cento (p=0,0043); e para comprimento de sarcômeros em G1= 3,51 por cento (p=0,3989) e G2= 5,28 por cento (p=0,1771). Conclui-se que duas semanas de remobilização através da natação, com diferentes tipos de sobrecarga não foram suficientes para reverter totalmente o processo de atrofia causado pela imobilização.

An important issue in rehabilitation is how to protect the skeletal muscle from immobilization effects, since it is the most changeable tissue amongst the biological tissues and responds to normal or modified demands with morphological and functional adaptations. The objective of this paper was to check the effect of two different swimming load intensities on the morphological properties of the soleus muscle, and if the different degrees of swimming are effective to reverse the process of atrophy caused by immobilization during 15 days. Ten rats, 10±2 weeks were used and divided in 2 groups:G1(immobilization/swimming without overload) and G2 (immobilization/swimming with 10 percent overload). Within the variable analyzed, when the left limb (submitted to immobilization) was compared with the right limb (not submitted) it was observed: for muscle weight G1=-20.55 percent (p=0.0344) and G2= -17.02 percent (p=0.0053); for muscle length G1= -10.66 percent (p=0.0011) and G2= -6.55 percent (p=0.1016); for serial sarcomere estimate G1= -14.18 percent (p=0.0101) and G2= -10.99 percent (p=0.0043); and sarcomere length G1= 3.51 percent (p=0.3989) and G2= 5.28 percent (p=0.1771). It has been concluded that two weeks of remobilization through swimming, with different degrees of overload, were not sufficient to reverse the atrophy process caused by immobilization.

Variation of sarcomere length, sarcomere number and tetanic tension of skeletal muscle during postnatal growth in mice / 体力科学

The purpose of present study was to investigate the relationship between the increase of sarcomere length, sarcomere number and tetanic tension of the extensor digitorum longus muscles during postnatal growth in mice. The following results were obtained ; 1) The cross-sectional area, length of muscle and fiber length increased rapidly up to 7th week. 2) The sarcomere number increased up to 9 th week, 3) The tetanic tension per cross-sectional area decreased significantly in 7 th week, 4) The maximum value of sarcomere length which was obtained at middle region of the fiber correlated significantly with the tetanic tension per cross-sectional area (the correlation coefficient : r=-0.675) . These observations suggest that the local expansion of sarcomere length during postnatal growth affects the tension development.

An experimental study on the length change of the sarcomere in rat during the rigor mortis / 中国法医学杂志

0 05),while in the second group there was significant difference( P