ABC | Volume 114, Nº2, February 2020

Original Article Quantification of DNA Damage in Different Tissues in Rats with Heart Failure Giuseppe Potrick Stefani, 1 R amiro Barcos Nunes, 1 Douglas Dalcin Rossato, 2 Vitor Scotta Hentschke, 1 Marlise Di Domenico, 1 Pedro Dal Lago, 1 Cláudia Ramos Rhoden 1 Universidade Federal de Ciências da Saúde de Porto Alegre, 1 Porto Alegre, RS – Brazil Centro Universitário Franciscano, 2 Santa Maria, RS – Brazil Mailing Address: Giuseppe Potrick Stefani • Universidade Federal de Ciências da Saúde de Porto Alegre - Sarmento Leite street, 245. Postal Code 90050-170, Porto Alegre, RS – Brazil E-mail: gpotrick@gmail.com Manuscript received September 03, 2018, revised manuscript April 06, 2019, accepted May 15, 2019 DOI: https://doi.org/10.36660/abc.20180198 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. (Arq Bras Cardiol. 2020; 114(2):234-242) Keywords: Heart Failure; Rats; Rats Inbred Strains; Tissue Distribution; DNA Damage; Comet Assay. Introduction Heart failure is a complex syndrome which characterizes structural and functional abnormalities in the heart in maintaining adequate blood demand. Chronic heart failure (CHF) affects approximately 1 to 2% of the population in developed countries and its prevalence increases at least 10% in senior adults. 1 One of the most common causes to heart failure is myocardial infarction (MI), which induces pathologic cardiac remodeling. 2 This syndrome does not affect only the heart, it also affects other organs, such as lungs and skeletal muscles. 3 CHF is characterized by changes in ventilatory mechanics which impair the uptake and supply of oxygen to the systems. Hypoperfusion, which is sustained with a ventricular dysfunction in a vicious cycle, induces oxidative stress in the majority of tissues. 4 Oxidative stress is a state in which the cell is in an oxidative imbalance, forming more reactive species than its neutralizing capacity. 5 It has been proposed elsewhere that oxidative stress biomarkers, such as concentration of malondialdehyde and uric acid, could enlighten the extent of oxidative damage and guide treatment in patients with CHF. 6 Since reactive oxygen species (ROS) can damage different biomolecules, such as lipids, proteins and DNA, the damage in nucleic acids has not been consistently investigated in CHF. A biomarker that has already been a target of investigation is the concentration of 8-hydroxy-2'-deoxyguanosine (8-OHdG). 7 However, its measurement mirrors the oxidative damage in one type of DNA lesion, which does not reflect the total damage in the DNA helix. For that, toxicological assays, such as the comet assay, have never been tested in CHF, aiming to assess global DNA damage in different tissues. This technique is broadly used in toxicological studies and is considered to be consistent, sensitive and highly reproductive. 8 The comet assay directly measures the extent of DNA damage, constituted by single and double DNA strand breaks. 9 This method allows its measurement in blood and all tissues of interest, expanding the analysis of local damage, and its correlation with physiological and functional parameters. 10 In heart failure, it is still not clear how the inability of the failing heart can affect different structures beyond the cardiovascular system, especially on DNA damage. Since in CHF there is a scenario of systemic oxidative damage as a function of the 234