Experimental Physiology –Research Paper: Exercise training combined with angiotensin II receptor blockade reduces oxidative stress after myocardial infarction in rats

Abstract

An increase in oxidative stress and decrease in antioxidant enzymes have been suggested to be involved in the pathophysiology of myocardial infarction (MI). In this study in rats, treadmill exercise training and losartan treatment began 1 week post-myocardial infarction (MI) and lasted 8 weeks. We evaluated the changes in the mRNA and protein expressions for the enzymatic antioxidants superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase after exercise and losartan treatment post-MI. Our results demonstrated that GPx and catalase mRNA levels were comparable among all the groups, while the mRNA level for manganese SOD (MnSOD) was significantly increased in exercise training with/without losartan treatment compared with the sedentary post-MI group. Moreover, the mRNA level for gp91 phox was dramatically decreased by a combination of exercise and losartan treatment. The protein levels for MnSOD were significantly elevated by exercise training in combination with losartan treatment. The protein levels for catalase were significantly increased in response to exercise, and further augmented by exercise together with losartan treatment. Thiobarbituric acid-reactive substances in plasma were significantly increased in the post-MI rats, but were decreased by exercise or losartan treatment, indicating that both exercise and losartan may reduce lipid oxidative damage. In addition, catalase and SOD enzymatic activities were significantly enhanced by exercise combined with losartan treatment. Our results suggest that exercise training improves catalase and MnSOD expression and attenuates oxidative stress. These effects are potentiated when combining exercise with angiotensin II receptor blockade.

Effects of Chronic Swimming Training and Oestrogen Therapy on Coronary Vascular Reactivity and Expression of Antioxidant Enzymes in Ovariectomized Rats

“…[53] As shown in Figure 3, the expression of catalase increased only in the trained group compared to the OVX group. Consistent with our findings, Kang et al [11] reported no changes in the coronary expression of catalase in response to ERT, and Xu et al [54] reported enhanced catalase expression and activity in cardiac muscle after exercise training in rats submitted to myocardial infarction.…”

Cardiac remodeling and function following exercise and angiotensin II receptor antagonism

“…They also reported that exercise and losartan mediated their eVects diVerently, with losartan further unloading the hemodynamic burden of the heart, and exercise training increasing metabolic enzyme activity, particularly creatine and adenylate kinase activities (Kemi et al 2007). Exercise plus losartan treatment has also been shown to improve catalase and MnSOD expression in the post-infarcted heart (Xu et al 2010). Thus, there are a host of reported hemodynamic and metabolic beneWts associated with exercise training and AT1 receptor blockade.…”

Losartan Improved Antioxidant Defense, Renal Function and Structure of Postischemic Hypertensive Kidney

“…Losartan can also prevent the increased concentration of H 2 O 2 caused by Ang II infusion [21]. In addition, it was shown that eight-week Losartan treatment leads to an increase of CAT activity in damaged cardiac tissue of Sprague-Dawley rats [22]. It is well-known that hydroxyl radical, one of the most reactive oxygen species, as a product of H 2 O 2 degradation (Fenton's reaction), has an important role in LP, but CAT decomposes H 2 O 2 to both electro-neutral H 2 O and O 2 molecules.…”