Defining the roles of NADPH oxidases in vascular remodelling and arterial hypertension

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Hypertension (high blood pressure) is a major risk factor for cardiovascular diseases such as heart attacks, heart failure and stroke - the major causes of death world-wide and a huge burden on the Australian health care budget. Oxidative stress, resulting from an imbalance in the production and removal of toxic molecules called free radicals within the blood vessel wall, is a key player in the initiation and progression of these disorders. In the early stages of hypertension, production of free radicals only just outweighs their removal, resulting in a mild oxidative stress. However, this is enough to trigger a cascade of downstream events leading to activation of other, normally dormant, free radical generating systems. At these excessive levels, free radicals attack the cells of the artery wall leading to blood vessel dysfunction and ultimately cardiovascular disease. A major source of free radicals in the blood vessel wall are a family of enzymes called NADPH oxidases. It is our hypothesis that upregulation of onr of these enzymes in the early stages of hypertension is the initial trigger for many of the downstream effects that ultimately lead to cardiovascular disease. Our group is uniquely poised to test this hypothesis as we are the only laboratory in the world with access to three different strains of genetically modified mice, each lacking one of the three known isoforms of NADPH oxidase. Identification of the specific isoform of NADPH oxidase involved in free radical production in blood vessels is a critical first step in developing drugs that block vascular free radical production and so remove the molecular link between hypertension and major cardiovascular events.