Recent studies have suggested that alterations in vascular smooth muscle cell signal transduction are the biochemcial progenitors of the hypertensive state. Signal transduction is accompanied by the activation of specific phospholipases which result in the production of several potent bioactive metabolites (e.g. eicosanoids, diglycerides, inositol trisphosphates) and accumulation of moieties which alter the molecular dynamics of the cell membrane (e.g lysophospholipids, phosphatidic acid, free fatty acids and diglycerides). The overall hypothesis of the proposed research is that strong bidirectional relationships exist between signal transduction, membrane molecular dynamics and propagation of the hypertensive state. First, the magnitude and temporal course of arachidonic acid and diglyceride production during signal transduction will be delineated, the contributions of each type of phospholipase activity to their production will be defined, and their subcellular loci of origin will be established. Alterations which become manifest during development of the hypertensive state will be delineated. Next, the proximal enzymic mediators of signal transduction in smooth muscle cells, phospholipases, will be purified and subjected to detailed kinetic analyses to identify the biochemical mechanisms responsible for their regulation. Antisense DNA strategies will be employed to define the role of each phospholipase in mediating specific physiologic and biochemcial aspects of signal transduction. Alterations in plasma membrane dynamics which occur during signal transduction or become manifest during development of the hypertensive state will be quantified. The functional sequelae of alterations in plasma membane molecular dynamics on ion flux, ion transport ad the kinetics of transmembrane enzymes will be identified. Taken together, the proposed research is a multidisciplinary approach focused on identifying the detailed molecular interactions which modulate signal transduction, membrane dynamics and the development of the hypertensive state.
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