Monitoring cytosolic free magnesium in cultured chicken heart cells by use of the fluorescent indicator Furaptra.
Cytosolic free magnesium concentration [Mg2+]i and its regulation were studied in cultured embryonic chicken heart cells by use of the fluorescent indicator 2-[2-(5-carboxy)oxazole]-5-hydroxy-6-aminobenzofuran-N,N,O-triacet ic acid (Furaptra). The intracellular location of Furaptra was confirmed by its complete release from cells upon addition of saponin. The basal [Mg2+]i, which averaged 0.48 +/- 0.03 mM (n = 31), increased 3-fold on perfusion with sodium-free solution. This increase could not simply be attributed to intracellular sodium-extracellular magnesium exchange because a similar increase in [Mg2+]i occurred with magnesium-free, sodium-free perfusion. Furthermore, the increase in [Mg2+]i was largely attenuated when calcium was removed from the sodium-free perfusate. Thus, a substantial part of the increase in [Mg2+]i that occurs upon sodium-free perfusion is dependent on an increase in cytosolic free calcium (intracellular sodium-extracellular calcium exchange). The data suggest that [Mg2+]i is altered by calcium, most likely due to a competition for intracellular binding sites.
Murphy
E
E
Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.
Freudenrich
C C
CC
Levy
L A
LA
London
R E
RE
Lieberman
M
M
D000818:Animals; D001572:Benzofurans; D002478:Cells, Cultured; D002642:Chick Embryo; D003600:Cytosol / Q000032:analysis; D016257:Fura-2 / Q000031:analogs & derivatives*; D008274:Magnesium / Q000032:analysis*; D009206:Myocardium / Q000032:analysis; D010080:Oxazoles; D013050:Spectrometry, Fluorescence; D013997:Time Factors
D001572:Benzofurans; D010080:Oxazoles; C058776:2-(2-(5-carboxy)oxazole)-5-hydroxy-6-aminobenzofuran-N,N,O-triacetic acid; D008274:Magnesium; D016257:Fura-2