This application is a competitive supplement to 2 R01 HL050598-09, the original grant that supports gap junction research in our laboratory. Virtually every component of this grant requires analysis of connexin expression and distribution using quantitative confocal immunofluorescence microscopy. Indeed, confocal microscopy has become the principle method we use to characterize connexin expression and distribution in gap junctions in virtually all in vitro and in vivo heart preparations used in research in our laboratory. We are facing serious limitations in our current confocal microscopy resource. These limitations stem from intense usage of aging equipment, and a pressing need to ensure the continued working order of our instrumentation through periodic maintenance and troubleshooting. In this application, we request funds for acquisition of additional equipment and implementation of a maintenance program that will ensure continued availability .of confocal microscopy resources for our research. [unreadable] [unreadable] [unreadable]