Aplicação de exercício isotônico durante a hemodiálise melhora a eficiência dialítica / Isotonic exercise during hemodialysis improves dialysis efficiency

INTRODUÇÃO: A doença renal crônica (DRC) é decorrente de uma lesão renal e perda progressiva e irreversível da função dos rins. A hemodiálise substitui parcialmente essa função, com o objetivo de corrigir as alterações metabólicas na DRC. Para acompanhar a adequação da diálise, é determinado o Kt/V - índice de depuração da ureia por sessão de hemodiálise. O exercício físico de moderada intensidade tem se mostrado de fundamental importância para melhorar os efeitos adversos ao tratamento dialítico. OBJETIVOS: Avaliar o Kt/V em indivíduos com DRC submetidos ao exercício físico isotônico de baixa intensidade durante a hemodiálise. MATERIAIS E MÉTODOS: Analisados dados de 15 voluntários de ambos os sexos, submetidos à hemodiálise três vezes por semana. Após duas horas do início da diálise, foi aplicado um protocolo de exercícios isotônicos de baixa intensidade de membros superiores e inferiores com duração de 30 minutos, por um período de três meses. Os valores do Kt/V foram comparados no período de três meses anteriores sem exercício e após três meses de exercício. RESULTADOS: A média dos valores do Kt/V nos três meses sem exercício foi de 1,13 ± 0,11 e após aplicação do programa de exercícios foi de 1,29 ± 0,12 (p < 0,05). CONCLUSÃO: O programa de exercício físico isotônico de baixa intensidade em pacientes com DRC, aplicados durante a sessão de diálise mostrou a melhora da eficiência dialítica.

INTRODUCTION: The chronic kidney disease (CKD) is due to a renal injury and progressive and irreversible loss of kidney function. Hemodialysis replace partially this function with the objective of correcting the metabolic changes in the DRC. To monitor the adequacy of dialysis is determined the Kt/V - rate of clearance of urea per session of dialysis. The exercise of moderate intensity has been of fundamental importance for improving the adverse effects of dialysis treatment. OBJECTIVES: To evaluate Kt/V in persons with CKD submitted the isotonic exercise of low intensity during hemodialysis. MATERIALS AND METHODS: It was analyzed data from 15 volunteers with CKD, both sexes, submitted to dialysis three times a week. After two hours of the start of dialysis, was applied a protocol of isotonic exercises with low intensity of upper and lower limbs lasting 30 minutes, for a period of three months. The values of Kt/V were compared in the period of three months without exercise and after three months (monthly average). The paired Student t test was used for statistical analysis (p < 0.05). RESULTS: The average values of Kt/V within three months without exercise was 1.13 ± 0.11 and after implementation of the program of exercises was 1.29 ± 0.12 (p < 0.05). CONCLUSION: The program of isotonic exercises of low intensity in patients with CKD applied during the session of dialysis improved the efficiency dialysis.

Skeletal muscles with antagonistic muscular actions: morphological, contractile and metabolic characteristics / Músculo esquelético con acción muscular antogonista: características metabólicas, contratiles y morfológicas

The muscles can perform the same function in a specific segment (muscles of fast and slow contraction), and at the same time be antagonistic in relation to muscular action (flexors or extensors). The present research aimed to study the morphology, frequency and metabolism of fiber types and the contractile characteristics of extensor and flexors muscles of rabbit. We studied muscles anterior tibialis (AT), flexor digitorum supeficialis (FDS), extensor digitorum longus (EDL) and posterior tibialis (PT). The muscles were submitted to the techniques HE, NADH-TR and myofibrillar ATPase. In EDL and PT extensor muscles, the frequencies of red (SO + FOG) and white fibers (FG) were 68.77 percent and 31.23 percent versus 58.87 percent and 41.13 percent, respectively. In the AT and FDS flexor muscles, these frequencies were 75.14 percent and 24.86 percent versus 73.89 percent and 26.11 percent, respectively. In extensor muscles, the percentage of slow contraction fibers was 8.05 percent in EDL and 9.74 percent in PT, and in fast contraction, 91.95 percent in EDL and 90.26 percent in PT. In flexors, the slow contraction frequencies were 12.35 percent in AT and 8.17 percent in FDS, and in fast contraction, 87.65 percent and 91.83 percent, respectively. Skeletal muscles with antagonistic muscular actions (flexors and extensors) the morphological, contractile and metabolic characteristics are identical.

Los músculos estriados esqueléticos pueden desempeñar la misma función en un segmento corporal específico (músculos decontracción rápida y lenta), y al mismo tiempo pueden ser antagonistas en relación a su acción muscular (flexores o extensores). El objetivo de esta investigación fue analizar la morfología, el metabolismo y la frecuencia de los tipos de fibras y las características contráctiles de músculos flexores y extensores del conejo. Fueron evaluados los músculos tibial anterior (TA), flexor superficial de los dedos (FDS), extensor largo de los dedos (EDL) y tibial posterior (TP). Los músculos fueron sometidos a las técnicas de Hematoxilina Eosina (HE), NADH-TR y ATPase miofibrilar. En los músculos extensores EDL y TP, las frecuencias de los tipos de fibras rojas (SO + FOG) y fibras blancas (FG) fueron de 68,77 por ciento y 31,23 por ciento versus 58,87 por ciento y 41,13 por ciento, respectivamente. En los músculos flexores TA y FDS estas frecuencias fueron 75,14 por ciento y 24,86 por ciento versus 73,89 por ciento y 26,11 por ciento, respectivamente. En los músculos extensores el porcentaje de fibras de contracción lenta fue 8,05 por ciento en el EDL y 9,74 por ciento en el TP; y las fibras de contracción rápida fue de 91,95 por ciento en el EDL y 90,26 por ciento en el TP. En los flexores la frecuencia de fibras de contracción lenta fue12,35 por ciento en el TA y 8,17 por ciento FSD, y las fibras de contracción rßpida fue 87,65 por ciento y 91,83 por ciento respectivamente. Músculos esqueléticos con acción muscular antagónica (flexores y extensores) poseen características morfológicas, contráctiles y metabólicas idénticas.

Efeito do treinamento físico com diferentes temperaturas nas características morfológicas do músculo sóleo de ratos / The effects of physical training under different temperatures on the morphologic characteristics of the rat soleus muscle

O presente estudo teve por objetivo avaliar o efeito de diferentes temperaturas no músculo sóleo de ratos submetidos ao treinamento físico. Quinze ratos, da linhagem Wistar, machos, com idade de 100 ± 10 dias e peso variando entre 300 e 350 gramas, foram divididos em: Grupo Controle (n=5), Grupo 12ºC (n=5) e Grupo 33ºC (n=5). Os animais do grupo controle não realizaram o treinamento. Os grupos experimentais 12ºC e 33ºC foram exercitados por 5 semanas, 3 vezes por semana, inicialmente por 15 minutos, sendo o tempo aumentado gradualmente até 60 minutos. Os animais foram sacrificados 24h após o último dia de corrida e amostras do músculo sóleo foram coletadas e congeladas em nitrogênio líquido. Cortes histológicos (8?m) foram submetidos à coloração por HE. No grupo G33ºC, os animais apresentaram grande dificuldade para realizar a corrida, mostrando sinais de fadiga e exaustão. A avaliação histológica do músculo sóleo do grupo controle mostrou fibras musculares com morfologia preservada, aspecto poligonal, núcleos periféricos e organizadas em fascículos pelo perimísio, envoltas pelo endomísio. As características morfológicas identificadas nos animais dos grupos G12ºC e G33ºC foram: fibras de diferentes diâmetros, hipertróficas, atróficas, splitting, intenso infiltrado inflamatório, edema, fagocitose e necrose. Este estudo morfológico encontrou lesões nos dois grupos treinados; não houve diferença no grau de lesão muscular nos dois grupos experimentais, porém os animais do grupo 12ºC não apresentaram dificuldades para realização da corrida. No conjunto, os resultados mostram que o protocolo de treinamento com temperaturas de 12ºC e 33ºC induziu lesões no músculo sóleo de rato.

This study assesses the effects of different temperatures on the rat soleus muscle submitted to physical training. Fifteen male 100±10 yrold, 300-350g, Wistar rats were divided into: Control Group (n=5), 12ºC Group (n=5) and 33ºC Group (n=5). Animals from Control Group performed no exercise. Animals from the experimental 12ºC and 33ºC Groups performed exercises for 5 weeks, 3 times a week, at fi rst for 15 min, increasing gradually to 60 min. The animals were sacrifi ced 24h after the last running day, and soleus muscle samples were collected and frozen in liquid nitrogen. Histological cuts (8?m) were HE-stained. In the 33ºC Group, the animals presented a great diffi cult to keep running, showing signs of fatigue and exhaustion. The histological analysis of the soleus muscle from Control Group showed muscle fi bers with preserved morphology, polygonal aspect, peripherals nucleus and organized in fascicles by perimysium involved by endomysium. The morphological characteristics identifi ed in the animals from the experimental 12ºC and 33ºC Groups were: different diameter fi bers, hypertrophic, atrophic, splitting, intense infl ammatory infi ltrate, edema, phagocytosis, and necrosis. This morphologic study showed injuries in both exercised groups; there was no difference in the muscular lesion grade between the two temperatures, and the best performance was from the 12ºC Group. After all, the result shows that the training protocol at 12ºC and 33ºC induced rat soleus muscle injuries.

Down-regulation of MyoD gene expression in rat diaphragm muscle with heart failure.

Diaphragm myopathy has been described in patients with heart failure (HF), with alterations in myosin heavy chains (MHC) expression. The pathways that regulate MHC expression during HF have not been described, and myogenic regulatory factors (MRFs) may be involved. The purpose of this investigation was to determine MRF mRNA expression levels in the diaphragm. Diaphragm muscle from both HF and control Wistar rats was studied when overt HF had developed, 22 days after monocrotaline administration. MyoD, myogenin and MRF4 gene expression were determined by RT-PCR and MHC isoforms by polyacrylamide gel electrophoresis. Heart failure animals presented decreased MHC IIa/IIx protein isoform and MyoD gene expression, without altering MHC I, IIb, myogenin and MRF4. Our results show that in HF, MyoD is selectively down-regulated, which might be associated with alterations in MHC IIa/IIx content. These changes are likely to contribute to the diaphragm myopathy caused by HF.

Heart failure alters MyoD and MRF4 expressions in rat skeletal muscle.

Heart failure (HF) is characterized by a skeletal muscle myopathy with increased expression of fast myosin heavy chains (MHCs). The skeletal muscle-specific molecular regulatory mechanisms controlling MHC expression during HF have not been described. Myogenic regulatory factors (MRFs), a family of transcriptional factors that control the expression of several skeletal muscle-specific genes, may be related to these alterations. This investigation was undertaken in order to examine potential relationships between MRF mRNA expression and MHC protein isoforms in Wistar rat skeletal muscle with monocrotaline-induced HF. We studied soleus (Sol) and extensor digitorum longus (EDL) muscles from both HF and control Wistar rats. MyoD, myogenin and MRF4 contents were determined using reverse transcription-polymerase chain reaction while MHC isoforms were separated using polyacrylamide gel electrophoresis. Despite no change in MHC composition of Wistar rat skeletal muscles with HF, the mRNA relative expression of MyoD in Sol and EDL muscles and that of MRF4 in Sol muscle were significantly reduced, whereas myogenin was not changed in both muscles. This down-regulation in the mRNA relative expression of MRF4 in Sol was associated with atrophy in response to HF while these alterations were not present in EDL muscle. Taken together, our results show a potential role for MRFs in skeletal muscle myopathy during HF.