Mechanistic consequences of cardiac oxidative stress

My primary thesis focus deals with understanding the mechanistic consequences of cardiac oxidative stress in non-ischemic cardiovascular complications settings including type I diabetes related cardiomyopathy (Section I), glutathione depletion murine model (Section II) and cocaine related cardiovascular complications (Section III). This thesis is intended to provide novel mechanistic insights into these complications so that specialized therapy can be developed to treat these complications. Murine models are becoming increasingly important in the mechanistic study of cardiovascular disease. Establishment of methods for physiological assessment in mice becomes more and more critical. Section IV deals with the appropriate use of chemicals for stress testing in mice in addition to basal cardiovascular function measurements having been developed previously.; Cardiovascular disease remains the leading cause of death in the United States, causing 38 percent of all deaths and killing about half a million people each year. Adults aren't the only ones at risk for cardiovascular diseases. Increasingly, children are at risk too. There is strong evidence indicating that inflammation is a major risk factor and strongly correlates with cardiovascular disease. Although the mechanism involved in inflammation related cardiovascular complications remains unclear, innate immune response is implicated as a potential mechanism. Studies are emerging suggesting increased inflammation markers, such as inflammatory cells, C-reactive protein (CRP) and cytokines, and especially oxidative stress as a consequence of inflammation, may play important roles in developing cardiovascular disease. They are associated with the pathogenesis of not only ischemic heart disease but also nonischemic settings, particularly relevant in pediatric populations. However, the mechanistic consequences of cardiac oxidative stress remain obscure.; Type I diabetes is associated with a unique form of cardiomyopathy in the absence of atherosclerosis. Redox imbalance and/or changes in vascular endothelial growth factor have been associated with diabetes related cardiomyopathy. The mechanisms of these changes and their inter-relationships are not clear. Using a murine type 1 diabetes model we tested the hypothesis that alterations in cardiac performance were associated with myocardial oxidative stress. We also investigated changes in microvascular prevalence, vascular endothelial growth factor (VEGF) isoforms and connexin isoforms as contributors to ventricular dysfunction. LV fractional shortening (FS%) was reduced at day 7 and 35 relative to age-matched controls. Alteration in ventricular conduction (QRS and QTc prolongation) was also observed, with no change in ST segment (e.g. no evidence of myocardial ischemia). GSH/GSSG ratio and VEGF isoforms were significantly reduced. Immunostaining for CD31 and digital image analysis demonstrated a 35% reduction in microvessels/myocardial area, evidence of rarefaction, which was highly correlated with FS%. In addition, changes in connexin 43 (Cx43) distribution were observed post-STZ (Type 1 diabetes model), as Cx43 staining was dispersed from intercalated disks, which was associated with QRS prolongation. These data demonstrate that the mouse model of STZ induced type-1 diabetes mimics the cardiovascular abnormalities observed in clinical settings with respect to non-ischemic contractile alterations, electrophysiological abnormalities and microvascular rarefaction and that these changes are related to oxidative stress, perturbations in myocardial VEGF and/or connexin regulation. These findings also implicate GSH depletion and/or GSSG accumulation as participants in this setting.; Recycling of GSH, with its disulfide product (GSSG) is a major component of intracellular redox regulation, but its contribution to cardiac function is not well defined. We tested the hypothesis that in vivo cardiac GSH depletion in normal mice causes increased...