Physical conditioning modulates rat cardiac vascular endothelial growth factor gene expression in nitric oxide-deficient hypertension

Abstract

Many individuals with cardiac diseases undergo periodic physical conditioning with or without medication to improve cardiovascular health. Therefore, this study investigated the interaction of physical training and chronic nitric oxide synthase (NOS) inhibitor (nitro-l-arginine methyl ester, l-NAME) treatment on blood pressure (BP), cardiac vascular endothelial factor (VEGF) gene expression, and nitric oxide (NO) systems in rats. Fisher 344 rats were divided into four groups and treated as follows: (1) sedentary control, (2) exercise training (ET) for 8 weeks, (3) l-NAME (10mg/kg, s.c. for 8 weeks), and (4) ET+l-NAME. BP was monitored with tail-cuff method. The animals were sacrificed 24h after last treatments and hearts were isolated and analyzed. Physical conditioning significantly increased respiratory exchange ratio, cardiac NO levels, NOS activity, endothelial eNOS, and inducible iNOS protein expression as well as VEGF gene expression. Training also caused depletion of cardiac malondialdehyde (MDA) levels indicating the beneficial effects of the training. Chronic l-NAME administration resulted in a depletion of cardiac NO level, NOS activity, and eNOS, nNOS, and iNOS protein expressions, as well as VEGF gene expression (2-fold increase in VEGF mRNA). Chronic l-NAME administration also enhanced cardiac MDA levels indicating cardiac oxidative injury. These biochemical changes were accompanied by increases in BP after l-NAME administration. Interaction of training and NOS inhibitor treatment resulted in normalization of BP and up-regulation of cardiac VEGF gene expression. The data suggest that physical conditioning attenuated the oxidative injury caused by chronic NOS inhibition by up-regulating the cardiac VEGF and NO levels and lowering the BP in rats.