Contraction Study of a Single Cardiac Muscle Cell in a Microfluidic Chip

This chapter introduces a microfluidic method to study the contraction of a single cardiac muscle cell (cardiomyocyte). This method integrates single-cell selection, cell retention, dye loading, chemical stimulation, and fluorescence measurement for intracellular calcium on one microfluidic chip. Before single-cell experiments, the bonded chip was modified in order to make the channel deep enough to accommodate a large, single cardiomyocyte. After the modification, a single heart muscle cell could be selected and retained at a cell retention structure. Fluo-4 AM was loaded in the cell for the measurement of intracellular calcium ion concentration in the cell. Subsequently, caffeine was introduced into the chamber to induce the contraction of the cardiomyocyte. During contraction, fluorescence measurement was used to monitor the intracellular calcium level, and an optical imaging system was used to monitor the shape to confirm the contraction. The resting [Ca²⁺ ]_i of cardiomyocyte was determined and was consistent with the value of approx 100 nM in the literature.