The purpose of this application is to establish a center for fluorescence digital imaging microscopy and image processing at Washington University. The major user group will employ this instrumentation to study fundamental aspects of hormonal control of cell calcium and hydrogen homeostasis in a broad range of tissues. Studies of signal transduction, receptor mediated endocytosis, cell growth and differentiation, chemotaxis, cell to cell interaction and cell-extracellular matrix interaction are incorporated in the studies proposed by the large major user group Each study represents an extension/new direction directly applicable to research funded by the PHS. Thus, the application represents in exciting opportunity to develop important new thrusts to the research of the user group. The principal investigator has developed technology for single cell recordings of intracellular Ca2+ and pH. The studies proposed using the new instrumentation represent critical extensions required of new information in the area of hormonal control of cell calcium homeostasis. This area includes mechanisms of calcium entry through the plasma membrane, interactions of the endoplasmic reticulum with the plasma membrane. and coordination of calcium entry and efflux mechanisms. The analysis of cell hydrogen metabolism, its role in chemotaxis and the relationship between pHi and (Ca2+)i will also be studied through this proposal. Subcellular distribution and regulation of subcellular compartments of (H+) and (Ca2+)i are major features of studies designed to analyze receptor mediated endocystosis, cell- extracellular matrix interaction and cell to cell communication. The use of specific fluorophores to study cell trafficking of substances are directly related/integrated into the above studies. The system requested is designed to determine the three dimensional histogram of fluorescent intensity of fluorophores associated with subcellular compartments in living cells with correction for interfering light emission. In addition, the system provides the capability to rapidly analyze microfluorimetric images, digitizing, them and analyzing them with cine and video images of movement. Thus, this project represents an opportunity for a large diverse user group to develop new information critical to the understanding of the hormonal physiology, cell biology, and pathophysiology of renal and osseous diseases.