ABC | Volume 110, Nº3, March 2018

Original Article Rodrigues et al Aerobic exercise training in β 1ARKO mice Arq Bras Cardiol. 2018; 110(3):256-262 1. Barretto AC, Santos AC, Munhoz R, Rondon MU, Franco FG, Trombetta IC, et al. Increased muscle sympathetic nerve activity predicts mortality in heart failure patients. Int J Cardiol. 2009;135(3):302-7. doi: 10.1016/j. ijcard.2008.03.056. 2. Braunwald E. Heart failure. JACC Heart Fail. 2013 Feb;1(1):1-20. doi: 10.1016/j.jchf.2012.10.002. 3. BristowMR, Ginsburg R, Minobe W, Cubicciotti RS, SagemanWS, Lurie K, et al. Decreased catecholamine sensitivity and beta-adrenergic-receptor density in failing human hearts. N Engl J Med. 1982;307(4):205-11. doi: 10.1056/NEJM198207223070401. 4. Wallukat G. The beta-adrenergic receptors. Herz. 2002;27(7):683-90. doi: 10.1007/s00059-002-2434-z. 5. Xiang Y, Kobilka BK. Myocyte adrenoceptor signaling pathways. Science. 2003;300(5625):1530-2. doi: 10.1126/science.1079206. 6. Bers DM. Cardiac excitation-contraction coupling . 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We believe that future studies using HIIT would provide interesting findings in this animal model. This study has limitations. First, we used global KO mice and systemic alterations confounding the exercise effects may have occurred, thus these results have to be interpreted with caution. Second, although WTt animals had improved their exercise capacity, unexpectedly their LV myocytes presented lower cell shortening than WTc mice. This finding really intrigued us, and, unfortunately, we cannot explain it. Conclusion In conclusion, MCAE training improves myocyte contractility in the left ventricle of β 1 ARKO mice. This finding has potential clinical implications and supports the therapeutic value of this type of exercise training in the treatment of heart diseases involving β 1 -AR desensitization or reduction. Author contributions Conception and design of the research: Rodrigues AC, Natali AJ, Brum PC, Prímola-Gomes TN; Acquisition of data: Rodrigues AC, Cunha DNQ, Costa AJLD, Moura AG; Analysis and interpretation of the data: Rodrigues AC, Natali AJ, Carneiro‑Júnior MA, Prímola-Gomes TN; Statistical analysis: Rodrigues AC, F lix LB;Writing of themanuscript: Rodrigues AC, Natali AJ, Prímola-Gomes TN; Critical revision of the manuscript for intellectual content: Natali AJ, Prímola-Gomes TN. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding This study was funded by CNPq, Fapemig, Capes and Fapesp. Study Association This article is part of the thesis of master submitted by Aurora Corrêa Rodrigues, from Universidade Federal de Vi osa. Ethics approval and consent to participate This study was approved by the Ethics Committee on Animal Experiments of the Universidade Federal de Vi osa under the protocol number #59/2012. 260