AT1 and Aldosterone Receptors Blockade Prevents the Chronic Effect of Nandrolone on the Exercise-Induced Cardioprotection in Perfused rat Heart Subjected to Ischemia and Reperfusion
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Myocardial tolerance to ischaemia/reperfusion (I/R) injury is improved by exercise training, but this cardioprotection is impaired by the chronic use of anabolic androgenic steroids (AAS). The present study evaluated whether blockade of angiotensin II receptor (AT1-R) with losartan and aldosterone receptor (mineralocorticoid receptor, MR) with spironolactone could prevent the deleterious effect of AAS on the exercise-induced cardioprotection.
Methods and Results
Male Wistar rats were exercised and treated with either vehicle, nandrolone decanoate (10 mg/kg/week i.m.) or the same dose of nandrolone plus losartan or spironolactone (20 mg/kg/day orally) for 8 weeks. Langendorff-perfused hearts were subjected to I/R and evaluated for the postischaemic recovery of left ventricle (LV) function and infarct size. mRNA and protein expression of angiotensin II type 1 receptor (AT1-R), mineralocorticoid receptor (MR), and KATP channels were determined by reverse-transcriptase polymerase chain reaction and Western blotting. Postischaemic recovery of LV function was better and infarct size was smaller in the exercised rat hearts than in the sedentary rat hearts. Nandrolone impaired the exercise-induced cardioprotection, but this effect was prevented by losartan (AT1-R antagonist) and spironolactone (MR antagonist) treatments. Myocardial AT1-R and MR expression levels were increased, and the expression of the KATP channel subunits SUR2a and Kir6.1 was decreased and Kir6.2 increased in the nandrolone-treated rat hearts. The nandrolone-induced changes of AT1-R, MR, and KATP subunits expression was normalized by the losartan and spironolactone treatments.
The chronic nandrolone treatment impairs the exercise-induced cardioprotection against ischaemia/reperfusion injury by activating the cardiac renin-angiotensin-aldosterone system and downregulating KATP channel expression.
KeywordsMyocardial ischaemia-reperfusion Exercise-induced cardioprotection Anabolic steroid Nandrolone Renin-angiotensin-aldosterone system ATP-dependent potassium channels
Source of Fundings
This work was supported by the FAPERJ–Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro (grant E-26/110.342/2012). JHMN is a research fellow from CNPq. SRMN received a fellowship from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).
Conflict of Interest
- 2.World Health Organization. Cardiovascular diseases (CVDs). Fact sheet No. 317, 2011.Google Scholar
- 9.Bowles DK, Farrar RP, Starnes JW. Exercise training improves cardiac function after ischemia in the isolated, working rat heart. Am J Physiol Heart Circ Physiol. 1992;263:H804–9.Google Scholar
- 23.Du Toit EF, Rossouw E, Van Rooyen J, Lochner A. Proposed mechanisms for the anabolic steroid-induced increase in myocardial susceptibility to ischemia/reperfusion injury. Cardiovasc J South Afr. 2005;16:21–8.Google Scholar
- 32.Nakamura K, Fushimi K, Kouchi H, Mihara K, Miyazaki M, Ohe T, et al. Inhibitory effects of antioxidants on neonatal rat cardiac myocyte hypertrophy induced by tumor necrosis factor-α and angiotensin II. 1998;98:794–9.Google Scholar
- 42.Sato M, Engelman RM, Otani H, Maulik N, Rousou JA, Flack III JE, et al. Myocardial protection by preconditioning of heart with losartan, na angiotensin II type 1-receptor blocker: implication of bradykinin-dependent and bradykinin-independent mechanisms. Circulation. 2000;102(Supl 3):346–51.Google Scholar