Reactive oxygen species (ROS) play a role in modulating angiogenesis. Principal among ROS are superoxide (O2-), hydrogen peroxide (H2O2), and products of the reactions between ROS and NO. Potential sources of ROS include NADPH oxidase, the mitochondrial electron transport chain, xanthine oxidase, NOS, cyclooxygenase, and lipoxy-genase. Recent studies have indicated that NADPH oxidase may be axiomatic in mediating angiogenesis. In keeping with the wound healing mechanisms described earlier, virtually all the factors that promote angiogenesis also promote the upregulation of vascular NADPH oxidase, including cytokines, peptide growth factors, angiotensin II, and TXA2. Hypoxia itself has also been shown to induce the expression of NADPH oxidase. It is of interest that copper is both a potent angiogenic factor as well as a catalyst for the generation of ROS. The mechanisms involved, however, are still obscure.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.