Cardiovascular diseases (CVD), such as hypertension, stroke, and coronary artery disease currently afflict millions of Americans and at an annual cost greater than $400 billion dollars. The mechanisms responsible for the pathogenesis of hypertension are not well understood and current treatments focus on the reduction of blood pressure, or the sequelae associated with it, rather than the contributing factors that lead to the disease. Transient Receptor Potential (TRP) channels, which have recently been shown to have an important role in the vasculature, present an exciting target for the development of novel treatment paradigms. Our recent findings demonstrate that TRPM4 mediates smooth muscle cell depolarization and vasoconstriction in response to both intraluminal pressure and receptor-dependent agonists. Recent reports have identified TRPC3 in agonist dependent vasoconstriction pathways. In addition, TRPC6 has been suggested to play a role in pressure-induced vasoconstriction pathways. All together, these findings suggest that TRPM4 acts as a downstream mediator of TRPC3 and TRPC6. Using electrophysiology, calcium imaging, and isolated vessel work in combination with RNAi technology, the current proposal will test the following three hypotheses;that TRPC3 and TRPC6 activity elicits calcium release from intracellular stores, that the calcium release from stores induces TRPM4 activity, and ultimately, that the proposed mechanism modulate vasoconstriction through agonist- and pressure-mediated pathways. The proposed studies will significantly enhance our understanding of the channel's regulation in the vasculature and further our knowledge of the roles of other TRP channels in modulating smooth muscle excitability. Relevance: The development of new preemptive treatments for hypertension is dependent on our understanding of the basic intrinsic mechanisms that control blood pressure. The proposed study will provide a novel molecular mechanism, as well as exciting potential targets for the development of novel treatments.
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