Real-Time Observations of Intracellular Mg2+ Signaling and Waves in a Single Living Ventricular Myocyte Cell

Despite the important regulatory role of Mg2+ in metabolic pathways, its underlying mechanism is not completely understood at the single-cell level. This study examined the propagation and dynamics of Mg2+ signaling across the cell membrane by employing the real-time visualization of intracellular Mg2+ waves in living ventricular myocytes using a combination of total internal reflection fluorescence microscopy and Nomarski differential interference contrast. Real-time Mg2+ waves and sparks in a living cell membrane were observed using a fluorescent Mg2+ indicator (mag-fluo-4-AM) in the concentration range of 5 aM-5 mu M. The intracellular locations of the fluorescent Mg2+ indicator were confirmed by adding Na(+)ATP. The Mg2+ sparks and waves showed random temporal propagation patterns in nonhomogeneous substructures. These results show that spatiotemporal intracellular Mg2+ signaling information can be obtained for individual living cells.