Protocol for dual-optical mapping of voltage and calcium sensors in human pluripotent stem cell-derived cardiomyocytes.

Simultaneous acquisition of fluorescent voltage and intracellular calcium signals requires spectrally distinct indicators and a high-speed imaging setup. Here, we present a protocol for the optical mapping of these key physiological parameters in human pluripotent stem cell-derived cardiomyocyte (hPSC-CM) monolayers. We describe steps for using spectrally compatible voltage and calcium sensors involving fluorescent dyes and genetically encoded sensors. We also detail procedures for building a driver capable of controlling light-emitting diodes (LEDs) in synchrony with a high-speed camera during image acquisition.