Quantification of DNA Damage in Different Tissues in Rats with Heart Failure.

BACKGROUND: Chronic heart failure (CHF) is a complex syndrome which comprises structural and functional alterations in the heart in maintaining the adequate blood demand to all tissues. Few investigations sought to evaluate oxidative DNA damage in CHF. OBJECTIVE: To quantify the DNA damage using the comet assay in left ventricle (LV), lungs, diaphragm, gastrocnemius and soleus in rats with CHF. METHODS: Twelve male Wistar rats (300 to 330 g) were selected for the study: Sham (n = 6) and CHF (n = 6). The animals underwent myocardial infarction by the ligation of the left coronary artery. After six weeks, the animals were euthanized. It was performed a cell suspension of the tissues. The comet assay was performed to evaluate single and double strand breaks in DNA. Significance level (p) considered < 0.05. RESULTS: The CHF group showed higher values of left ventricle end-diastolic pressure (LVEDP), pulmonary congestion, cardiac hypertrophy and lower values of maximal positive and negative derivatives of LV pressure, LV systolic pressure (p < 0.05). CHF group showed higher DNA damage (% tail DNA, tail moment and Olive tail moment) compared to Sham (p < 0.001). The tissue with the highest damage was the soleus, compared to LV and gastrocnemius in CHF group (p < 0.05). CONCLUSION: Our results indicates that the CHF affects all tissues, both centrally and peripherically, being more affected in skeletal muscle (soleus) and is positively correlated with LV dysfunction.

Quantification of DNA Damage in Different Tissues in Rats with Heart Failure / Quantificação de Dano em DNA em Diferentes Tecidos em Ratos com Insuficiência Cardíaca

Abstract Background: Chronic heart failure (CHF) is a complex syndrome which comprises structural and functional alterations in the heart in maintaining the adequate blood demand to all tissues. Few investigations sought to evaluate oxidative DNA damage in CHF. Objective: To quantify the DNA damage using the comet assay in left ventricle (LV), lungs, diaphragm, gastrocnemius and soleus in rats with CHF. Methods: Twelve male Wistar rats (300 to 330 g) were selected for the study: Sham (n = 6) and CHF (n = 6). The animals underwent myocardial infarction by the ligation of the left coronary artery. After six weeks, the animals were euthanized. It was performed a cell suspension of the tissues. The comet assay was performed to evaluate single and double strand breaks in DNA. Significance level (p) considered < 0.05. Results: The CHF group showed higher values of left ventricle end-diastolic pressure (LVEDP), pulmonary congestion, cardiac hypertrophy and lower values of maximal positive and negative derivatives of LV pressure, LV systolic pressure (p < 0.05). CHF group showed higher DNA damage (% tail DNA, tail moment and Olive tail moment) compared to Sham (p < 0.001). The tissue with the highest damage was the soleus, compared to LV and gastrocnemius in CHF group (p < 0.05). Conclusion: Our results indicates that the CHF affects all tissues, both centrally and peripherically, being more affected in skeletal muscle (soleus) and is positively correlated with LV dysfunction.

Resumo Fundamento: A insuficiência cardíaca crônica (ICC) é uma síndrome complexa que compreende alterações estruturais e funcionais no coração, mantendo demanda sanguínea adequada a todos os tecidos. Poucas investigações procuraram avaliar o dano oxidativo ao DNA na ICC. Objetivo: Quantificar o dano ao DNA utilizando o ensaio cometa no ventrículo esquerdo (VE), pulmões, diafragma, gastrocnêmio e sóleo em ratos com ICC. Métodos: Doze ratos Wistar machos (300 a 330 g) foram selecionados para o estudo: placebo (n = 6) e ICC (n = 6). Os animais foram submetidos a infarto do miocárdio através de ligadura da artéria coronária esquerda. Após seis semanas, os animais foram sacrificados. Foi realizada uma suspensão celular dos tecidos. O ensaio cometa foi realizado para avaliar as quebras de fita simples e dupla no DNA. Nível de significância (p) < 0,05. Resultados: O grupo ICC apresentou maiores valores de pressão diastólica final do ventrículo esquerdo (PDFVE), congestão pulmonar, hipertrofia cardíaca e menores valores de derivados máximos positivos e negativos da pressão do VE, pressão sistólica do VE (p < 0,05). O grupo ICC apresentou maior dano ao DNA (% de DNA da cauda, momento da cauda e momento da cauda de Olive) em comparação ao placebo (p < 0,001). O tecido com maior dano foi o sóleo, comparado ao VE e ao gastrocnêmio no grupo ICC (p < 0,05). Conclusão: Nossos resultados indicam que a ICC afeta todos os tecidos, de maneira central e periférica, sendo mais afetada no músculo esquelético (sóleo) e está positivamente correlacionada com a disfunção do VE.

Effects of creatine supplementation associated with resistance training on oxidative stress in different tissues of rats.

BACKGROUND: Creatine supplementation is known to exert an effect by increasing strength in high intensity and short duration exercises. There is a hypothesis which suggests that creatine supplementation may provide antioxidant activity by scavenging Reactive Oxygen Species. However, the antioxidant effect of creatine supplementation associated with resistance training has not yet been described in the literature. Therefore, we investigated the effect of creatine monohydrate supplementation associated with resistance training over maximum strength gain and oxidative stress in rats. METHODS: Forty male Wistar rats (250-300 g, 90 days old) were randomly allocated into 4 groups: Sedentary (SED, n = 10), Sedentary + Creatine (SED-Cr, n = 10), Resistance Training (RT, n = 10) and Resistance Training + Creatine (RT-Cr, n = 10). Trained animals were submitted to the RT protocol (4 series of 10-12 repetitions, 90 second interval, 4 times per week, 65% to 75% of 1MR, for 8 weeks). RESULTS: In this study, greater strength gain was observed in the SED-Cr, RT and RT-Cr groups compared to the SED group (P < 0.001). The RT-Cr group showed a higher maximum strength gain when compared to other groups (P < 0.001). Creatine supplementation associated with resistance training was able to reduce lipoperoxidation in the plasma (P < 0.05), the heart (P < 0.05), the liver (P < 0.05) and the gastrocnemius (P < 0.05) when compared to control groups. However, the supplementation had no influence on catalase activity (CAT) in the analyzed organs. Only in the heart was the CAT activity higher in the RT-Cr group (P < 0.05). The activity of superoxide dismutase (SOD) was lower in all of the analyzed organs in the SED-Cr group (P < 0.05), while SOD activity was lower in the trained group and sedentary supplemented group (P < 0.05). CONCLUSIONS: Creatine was shown to be an effective non-enzymatic antioxidant with supplementation alone and also when it was associated with resistance training in rats.