Interaction of physical training and chronic nitroglycerin treatment on blood pressure, nitric oxide, and oxidants/antioxidants in the rat heart

Many individuals with cardiovascular diseases undergo physical conditioning with or without medication. Therefore, this study investigated the interaction of exercise training and chronic nitroglycerin treatment on blood pressure (BP) and changes in cardiac nitric oxide (NO) and antioxidants in rats. Fisher 344 rats were divided into four groups treated as: (1) sedentary control, (2) exercise training for 8 weeks, (3) nitroglycerin (15 mg/kg, s.c. for 8 weeks), and (4) training + nitroglycerin for 8 weeks. Respiratory exchange ratio (RER), BP, and heart rate (HR) were monitored weekly for 8 weeks. The animals were sacrificed 24 h after last treatments, hearts isolated, and analyzed. Physical conditioning significantly increased RER, cardiac NO levels, and endothelial eNOS protein expression. Training significantly enhanced cardiac glutathione (GSH) levels, GSH/GSSG ratio, and the up-regulation of cardiac copper/zinc-superoxide dismutase (CuZn-SOD), manganese (Mn)-SOD, catalase (CAT), glutathione peroxidase (GSH-Px) activities, and protein expression. Training also caused depletion of cardiac malondialdehyde (MDA) and protein carbonyls with a significant increase in RER without any change in BP and HR. Chronic nitroglycerin administration significantly increased cardiac NO levels and eNOS protein expression. Nitroglycerin administration significantly enhanced cardiac Mn-SOD, CAT, and GST activities, and protein expression with decreased MDA levels and BP. Interaction of training and chronic nitroglycerin treatment increased cardiac NO levels with enhanced eNOS and iNOS protein expressions, GSH/GSSG ratio, and the up-regulation of antioxidant enzymes. This interaction normalized BP and HR and increased RER. The data suggest that the interaction of physical training and chronic nitroglycerin treatment resulted in the maintenance of BP and RER by up-regulating the antioxidants and NO levels and by reducing the oxidative stress in the rat heart. (C) 2003 Elsevier Science Ltd. All rights reserved.