Spatiotemporal Visualization of Intracellular Ca²⁺ in Living Heart Muscle Cells Viewed by Confocal Laser Scanning Microscopy

抄録

Ca²⁺ ions play pivotal roles in the excitation and contraction-relaxation processes of heart muscle cells. The advent of digital-imaging techniques, especially confocal laser scanning microscopy, as well as Ca²⁺-sensitive fluorescent dyes, has contributed substantially to the precise understanding of the spatiotemporal aspects of the intracellular Ca²⁺ dynamics in cardiomyocytes. In this review article, we review the progress in the cytochemical and histochemical researches on the intracellular Ca²⁺ concentration ([Ca²⁺]_i) of the heart. Recent imaging technologies have revealed that subcellular [Ca²⁺]_i dynamics are spatiotemporally heterogeneous under certain pathological conditions. We focus on the Ca²⁺ waves, i.e., representative of abnormal [Ca²⁺]_i dynamics that emerge under [Ca²⁺] _i-overloaded conditions, analyzed in preparations ranging from the enzymatically isolated myocytes to the whole heart. The pathophysiological significance of Ca²⁺ waves in the heart is also discussed.