Bioimaging for Study of the Myocardial Function: Fluorescence Microscopy Featuring the Na⁺-Ca²⁺ Exchanger

Abstract

In this review, we provide an overview of our studies on the myocardial Na⁺-Ca²⁺ exchanger, an antiporter located on the sarcolemma that catalyzes the electrogenic exchange of three Na⁺ and one Ca²⁺, either in the Ca²⁺ efflux (forward) or Ca²⁺ influx (reverse) modes. Firstly, an inhibitor of the Na⁺-Ca²⁺ exchanger was evaluated by fluorescence microscopy and a kinetic analysis. Secondly, intracellular Ca²⁺ oscillations were observed by rapid scanning confocal microscopy and the role of the forward-mode Na⁺-Ca²⁺ exchanger in myocardial excitation was clarified. Thirdly, the involvement of the reverse-mode Na⁺-Ca²⁺ exchanger in cellular damage during myocardial ischemia and reperfusion was demonstrated with various fluorescent probes. Our research was supported by bioimaging technology in combination with electrophysiology and pharmacology. Bioimaging is a powerful methodology in modern biology. With some caution and effort to optimize the technology to meet research needs, bioimaging would be fruitful for all researchers.