Real-time observations of intracellular Mg2+ signaling and waves in a single living ventricular myocyte cell.

Despite the important regulatory role of Mg(2+) in metabolic pathways, its underlying mechanism is not completely understood at the single-cell level. This study examined the propagation and dynamics of Mg(2+) signaling across the cell membrane by employing the real-time visualization of intracellular Mg(2+) waves in living ventricular myocytes using a combination of total internal reflection fluorescence microscopy and Nomarski differential interference contrast. Real-time Mg(2+) waves and sparks in a living cell membrane were observed using a fluorescent Mg(2+) indicator (mag-fluo-4-AM) in the concentration range of 5 aM-5 muM. The intracellular locations of the fluorescent Mg(2+) indicator were confirmed by adding Na(+)ATP. The Mg(2+) sparks and waves showed random temporal propagation patterns in nonhomogeneous substructures. These results show that spatiotemporal intracellular Mg(2+) signaling information can be obtained for individual living cells.