High-sodium intake aggravates myocardial injuries induced by aldosterone via oxidative stress in Sprague-Dawley rats

Abstract

Aim:To evaluate the effects of aldosterone with or without high sodium intake on blood pressure, myocardial structure and left ventricular function in rats, and to investigate the mechanisms underlying the effects.Methods:Eight- week-old male Sprague-Dawley rats were randomly divided into 3 groups: (1) control (CON) group fed a normal sodium diet, (2) aldosterone (ALD) group receiving aldosterone infusion and a normal sodium diet, and (3) high sodium plus aldosterone (HS-ALD) group receiving 1% NaCl diet in conjunction with aldosterone infusion. Aldosterone was administered through continuously subcutaneous infusion with osmotic minipump at the rate of 0.75g/h for 8 weeks. The myocardium structure was observed using transthoracic echocardiography and transmission electron microscopy. The collagen deposition in left ventricle was evaluated with Masson's trichrome staining. The expression of IL-18, p22phox, and p47phox proteins was examined using Western blot analysis.Results:The systolic blood pressure in the ALD and HS-ALD groups was significantly higher than that in the CON group after 2-week treatment. But the blood pressure showed no significant difference between the HS-ALD and ALD groups. The left ventricular hypertrophy, myocardial collagen deposition and oxidative stress were predominantly found in the HS-ALD and ALD group. Furthermore, the breakdown of myocardial structure and oxidative stress were more apparent in the HS-ALD group as compared with those in the ALD group.Conclusion:Long-term infusion of aldosterone results in hypertension and profibrotic cardiovascular responses in rats fed a normal sodium diet, which were mediated by oxidative stress. High-sodium intake could aggravate myocardial injuries induced by aldosterone. © 2012 CPS and SIMM All rights reserved.