Effects of vibration on the expression of mitochondrial fusion and fission genes and ultrastructure of skeletal muscle in rabbits / 中华劳动卫生职业病杂志

Objective: To study the effects of vibration on the expression of mitochondrial fusion and fission genes and ultrastructure of skeletal muscle in rabbits. Methods: Thirty-two 3.5-month-old New Zealand rabbits were randomly divided into low-intensity group, medium-intensity group, high-intensity group and control group, with 8 rabbits in each group. The rabbits in the experimental group were subjected to hind limb vibration load test for 45 days. The vibration intensity of the high intensity group was 12.26 m/s(2), the medium intensity group was 6.13 m/s(2), and the low intensity group was 3.02 m/s(2) according to the effective value of weighted acceleration[a(hw (4))] for 4 hours of equal energy frequency. The control group was exposed to noise only in the same experimental environment as the medium-intensity group. The noise levels of each group were measured during the vibration load experiment. After the test, the mRNA expression of mitochondrial fusion gene (Mfn1/Mfn2) and fission gene (Fis1, Drp1) by RT-PCR in the skeletal muscles were measured and the ultrastructure of the skeletal muscles were observed in high intensity group. Results: The mRNA expression of mitochondrial in the skeletal muscle tissues of control group, low intensity group, medium intensity group and high intensity group were Mfn1: 3.25±1.36, 3.85±1.90, 4.53±2.31 and 11.63±7.68; Mfn2: 0.68±0.25, 1.02±0.40, 0.94±0.33 and 1.40±0.45; Fis1: 1.05±0.62, 1.15±0.59, 1.53±1.06 and 2.46±1.51 and Drp1: 3.72±1.76, 2.91±1.63, 3.27±2.01 and 4.21±2.46, respectively. Compared with the control group, the expressions of Mfn1 mRNA, Mfn2 mRNA and Fis1 mRNA in the high-intensity group increased significantly (P<0.05) , and the expressions of Mfn2 mRNA in the medium-intensity group and the low-intensity group increased significantly (P<0.05) . Compared with the control group, the ultrastructure of skeletal muscle of high intensity group showed mitochondrial focal accumulation, cristae membrane damage, vacuole-like changes; Z-line irregularity of muscle fibers, and deficiency of sarcomere. Conclusion: Vibration must be lead to the abnormal mitochondrial morphology and structure and the disorder of energy metabolism due to the expression imbalance of mitochondrial fusion and fission genes in skeletal muscles of rabbits, which may be an important target of vibration-induced skeletal muscle injury.

Neovascularization after ischemic injury: evaluation with 99mTc-HYNIC-RGD / Neovascularização após lesão isquêmica: avaliação com 99mTc-HYNIC-RGD

Purpose: Angiogenesis involves many mediators including integrins, and the tripeptide RGD is a target amino acid recognition sequence for many of them. Hindlimb ischemia is a simple and convenient animal model however standardization of the injection procedures in the devascularized and control limb is lacking, thus rendering difficult the interpretation of results. The aim of this investigations was to evaluate neovascularization in a hindlimb murine model by means of 99mTc-HYNIC-ß-Ala-RGD. Methods: 99mTc-HYNIC-RGD analog was prepared using coligands. Ischemia was induced in Wistar rats by double- ligation of the common femoral artery. Radiolabeled RGD was injected after 2h, as well as 1, 3, 5, 7, 10 and 14 days. Uptake was evaluated by planar imaging and biodistribution studies. Results: The highest ratio between ischemia and control was achieved at the 7th day (2.62 ± 0.95), with substantial decrease by the 14th day. For pertechnetate the 7th day ratio was 0.87 ± 0.23. Scintigraphic image confirmed different uptakes. Conclusion: 99mTc-HYNIC-RGD analog concentrated in ischemic tissue by the time of widespread angiogenesis and pertechnetate confirmed reduction in blood flow. In this sense, the protocol can be recommended for ischemic models.

Objetivo: A angiogênese em resposta a fenômenos isquêmicos envolve vários mediadores como as integrinas, sendo que o tripeptídeo RGD possui uma seqüência de aminoácidos com reconhecimento para este alvo. O modelo animal de isquemia de pata traseira é simples e conveniente, porém não há uma padronização do procedimento de injeção e controle radioisotópico em membro desvascularizado, dificultando, portanto a interpretação de resultados. O objetivo deste estudo foi avaliar a neovascularização em modelo murino de isquemia de pata traseira através do radiotraçador 99mTc-HYNIC-ß-Ala-RGD. Métodos: O análogo 99mTc-HYNIC-RGD foi preparado usando coligantes. A isquemia foi induzida em ratos Wistar por dupla-ligação da artéria femoral comum na prega inguinal. Peptídeo RGD radiomarcado foi injetado após 2h, assim como 1, 3, 5, 7, 10 e 14 dias. A captação foi avaliada por imagem planar e estudos de biodistribuição. Resultados: A maior diferença de captação entre isquemia e pata controle foi obtida no 7º dia (2,62 ± 0,95), com decréscimo acentuado no 14º dia. Para o pertecnetato a razão no 7º dia foi 0,87 ± 0,23. A imagem cintilográfica confirmou as diferentes captações. Conclusões: O análogo 99mTc-HYNIC-RGD concentrou-se no tecido isquêmico na etapa em que a angiogênese é mais acentuada, e o estudo do pertecnetato confirmou a redução no fluxo sanguíneo. Desta maneira, este protocolo diagnóstico pode ser recomendado para modelos isquêmicos.

Estimulação elétrica minimiza alterações metabólicas musculares durante e após a imobilização de membro posterior de ratos / Electrical stimulation minimizes muscle metabolic alterations during and after immobilization of rats hindlimb

O objetivo do estudo foi avaliar o efeito da etimulação elétrica (EE) no perfil metabólico e no peso muscular de membro posterior de ratos durante a imobilização e após a retirada da órtese...

This study aimed at assessing the effect of electrical stimulation (ES) in muscles metabolic profile and weight of rat hindlimb during the limb immobilization period and after casts were removed...

Effects of L-alanyl-glutamine upon the blood and kidney biochemical parameters in the rat hind limb model of ischemia/reperfusion

OBJETIVO: Investigar alterações dos parâmetros metabólicos no sangue e rim de ratos submetidos à isquemia/reperfusão do membro pélvico. MÉTODOS: Quarenta e oito ratos machos foram distribuídos aleatoriamente em 2 grupos pré-tratados com administração intragástrica de solução salina 2,0 mL (G-1) ou L-alanil-glutamina 0,75 mgKg-1(G-2), uma vez ao dia (7:00h) durante 7 dias. Uma hora após a última gavagem todos os ratos foram anestesiados com éter dietílico, laparotomizados e submetidos ao pinçamento da artéria de ilíaca esquerda, durante 3 horas. Amostras foram coletadas ao término de isquemia e durante a reperfusão (1-3-6h) para determinação das concentrações in vivo de piruvato, lactato, glicose e corpos cetônicos (rim e sangue) e ATP (rim). RESULTADOS: Lactacemia e cetonemia aumentaram no grupo G-2 quando comparadas às aferidas em ratos não-tratados, durante a reperfusão. As concentrações de piruvato diminuíram e de lactato aumentaram significativamente no rim, durante a reperfusão (1h, 3h) em ratos do G-2 comparados aos respectivos controles. Houve um aumento significante nas concentrações renais de glicose, ATP e corpos cetônicos nos ratos tratados com L-alanil-glutamina durante a reperfusão (3h). CONCLUSÕES: A isquemia do membro pélvico em ratos pré-tratados com L-alanil-glutamina induz aumento da lactacemia e da concentração de lactato renal, indicando atividade glicolítica aumentada na medula renal. A hipercetonemia induzida pela oferta do dipeptídeo sugere cetogênese elevada, sinalizada por possível queda nas concentrações plasmáticas de insulina resultante da maior oxidação de glicose e utilização desse hormônio em tecidos periféricos.

Lack of hypophosphatemic effect on glucose uptake, lactate and pyruvate release by the normal rat perfused hind-limb

In previous experiments, it was observed that in the perfused hind-limb of phosphorus deficient rats there was a faster utilization of glucose when compared with preparations obtained from ad-libitum fed rats but similar to that obtained from pair-weighed rats. A greater release of lactate under the influence of insulin and a marked spontaneous and insulin induced liberation of pyruvate was registered in the perfused hind-limb of the phosphorus deficient rat. Since a hypophosphatemic medium was employed, we though it would be interesting to study the effect of low perfusate Pi in normal rat hind-limb preparations and, additionally, to observe it fast changes in the level of medium orthophosphate from normal to low values and viceversa were able to determine changes in glucose uptake and lactate and pyruvate release. In one group of experiments, the hind-limb of normal rats was perfused successively with orthophosphate deprived medium for thirty minutes in each stage. In another group of experiments, the first stage was carried out with normal. Pi medium, the second with orthophosphate deprived medium, and the third with normal Pi medium; each stage lasted thirty minutes. In all the experiments there was a gradual release of orthophosphate. The glucose uptake was not modified by the fast changes in the medium Pi nor were significant differences in lactate and pyruvate release observed, which showed clear increases in all stages. It is concluded that hypophosphatemia alone is not sufficient to obtain greater increases of lactate and pyruvate release; it is also required that the hind-limb preparations be obtained from ..