Objectives: To examine effects of pinacidil on intracellular free calcium concentration of cardiomyocytes during hypoxia/reoxygenation. Methods:A cell culture model of neonatal rat cardiac myocytes was used. There were three groups, including control group, hypoxia/reoxygenation group and pinacidil group. Confocal microscope was used with Fluo 3/AM as calcium indicator to detect changes of intracellular free calcium concentration. Results:The intracellular fluoresence intensity of singular cardiomyocyte in hypoxia/reoxygenation group was significantly higher than that of the controls( P