The goal of this project is to define the mechanisms by which arachidonate metabolism is regulated in cardiac cell types that actively produce prostaglandins and related compounds (""""""""eicosanoids""""""""). Eicosanoids have been implicated in cardiac diseases by several lines of evidence and are important modulators of inflammation in other tissues. Thus, production of these compounds by cardiac cells may influence myocardial repair, myocarditis, and pericariditis. In other cell types that have been studied, eicosanoid production is tightly regulated. Although much is known about the regulation in some cells, e.g., platelets, the precise mechanisms have yet to be unequivocally established in any cell type, and there is evidence that the processes vary among different types of cells. In this project the inital aim is to establish and identify cultures of bovine pericardial mesothelial cells, and of fibroblast-like cells from both normal and infarcted ventricular myocardium (obtained from dogs). These cell types have been chosen since they exhibit active production of eicosanoids (in contrast to myocytes) that are potentially relevant in cardiac pathophysiology. Subsequent aims are to identify and quantitate the eicosanoids that each cell type produces; define agonists for the stimulation of eicosanoid production for each; and, characterize the enzymatic steps that regulate the production. The effect(s) of clinically useful inhibitors of eicosanoid production and of changes in lipid content that might result from various dietary alterations will be studied. The analytical techniques developed for identification and quantitation of the products of cultured cells also will be used to assay samples of human pericardial fluid. The methodology will include cell culture, the examination of metabolic pathways in whole cells by radiolabeling studies, specific enzymatic assays on broken cell preparations, and analytical techniques such as various forms of chromatography, immunoassay, and spectrometry. These studies should define the mechanisms for regulating eicosanoid production in these heart cells and provide a scientific basis for attempts to manipulate the production in disease states. Further, the development of cell-culture systems will allow experimental approaches that may elucidate generalized mechanisms for regulation of arachidonate metabolism, and for the study of other metabolic processes in these cells (e.g., protein synthesis and secretion).
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