Measurement of electrical conduction properties of intact embryonic murine hearts by extracellular microelectrode arrays.

The study of the embryonic development of the cardiac conduction system and its congenital and toxicological defects requires protocols to measure electrical conduction through the myocardium. However, available methods either lack spatial information, necessitate the hearts to be sliced and mounted, or require specialized equipment. Microelectrode arrays (MEAs) are plates with embedded surface electrodes to measure localized extracellular ionic currents (field potentials) created by the depolarization and repolarization of cultured cells and tissue slices. Here we describe a protocol using MEAs to examine electrical conduction through intact and beating cultured hearts isolated from mouse embryos at 10.5 days postcoitus. This method allows measurements of conduction time, estimates of conduction velocity, atrioventricular conduction delay and block, and heart rate and rhythmicity.