harmacological elimination of motion artifacts during optical maging of cardiac tissues: Is blebbistatin the answer?

t r i i n 0 m F u p e s d p r u c Since the first measurements of action potentials with oltage-sensitive dyes from the epicardial surface of the rog heart by Salama and Morad, the field of optical imging of cardiac electrical activity has evolved dramatically rom cellular and subcellular levels to tissue and whole eart physiology, thanks to rapid advancement in optical echnology. While optical techniques have been used prinipally to map cardiac electrical activity on the heart surace, fiber-optic probes that enable simultaneous intramural ptical recordings at multiple sites in the heart have also een developed. High-resolution optical recording of elecrical activity using fluorescent dyes provides simultaneous oncontact recording of action potentials from multiple adacent sites at various scales of resolution in the whole heart nd multicellular cardiac tissue preparations. Because the umber of photodetectors may be increased without incuring increased injury to the tissue, optical methods enable igh spatiotemporal resolution of electrical activity that is nattainable by conventional techniques. Another advanage of optical methods is the ability to obtain direct detecion of repolarization simultaneously with recording of acivation by dynamic sampling of transmembrane potential hanges, as compared with conventional mapping, which rovides indirect data on repolarization that is calculated rom extracellular electrograms. Accordingly, high-resoluion optical mapping has become a common research tool in asic cardiac electrophysiology, especially in the investigaion of electrophysiologic mechanisms by which convenional electrical recordings are hampered by inadequate reslution or by a lack of precise information on repolarization. In spite of the growing application of optical mapping to ardiac electrophysiology, many technical problems persist nd hamper the utility of this technique. Particularly probematic are muscle contractions and associated heart wall otion, which distort optical recordings, the so-called moion artifacts. Various techniques have been used to reduce