Magnesium is an essential element for all living systems. The quantification of free intracellular Mg(2+) concentration (Mg(2+)(i)) is of utmost importance since changes in its basal value may be an ...indication of different pathologies due to abnormalities of Mg(2+) metabolism. In this work we used (31)P NMR and fluorescence spectroscopy to determine the resting Mg(2+)(i) in bovine chromaffin cells, a neuron-like cellular model, as well as confocal laser scanning microscopy to study the free Mg(2+) spatial distribution in these cells. (31)P NMR spectroscopy did not prove to be effective for the determination of Mg(2+)(i) in this particular case due to some special morphological and physiological properties of this cell type. A basal Mg(2+)(i) value of 0.551 +/- 0.008 mM was found for these cells using fluorescence spectroscopy and the Mg(2+)-sensitive probe furaptra; this value falls in the concentration range reported in the literature for neurons from different sources. This technique proved to be an accurate and sensitive tool to determine the Mg(2+)(i).lntraceilular free Mg(2+) seems to be essentially localized in the nucleus and around it, as shown by confocal microscopy with the Mg(2+)-sensitive probe Magnesium Green. It was not possible to derive any conclusion about free Mg(2+) localization inside the chromaffin granules and/or in the cytoplasm due to the lack of sufficient spatial resolution and to probe compartmentalization.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Li + influx by bovine chromaffin cells, obtained from bovine adrenal medulla, was studied in intact cell suspensions using 7 Li NMR spectroscopy with the shift reagent Tm(HDOTP) 4- . The influx rate ...constants, k i , were determined in the absence and in the presence of two Na + membrane transport inhibitors. The values obtained indicate that both voltage sensitive Na + channels and (Na + /K + )‐ATPase play an important role in Li + uptake by these cells. 7 Li NMR T 1 and T 2 relaxation times for intracellular Li + in bovine chromaffin cells provided a T 1 /T 2 ratio of 305, showing that Li + is highly, immobilized due to strong binding to intracellular structures. Using fluorescence spectroscopy and the Mg 2+ fluorescent probe, furaptra, the free intracellular Mg 2+ concentration in the bovine chromaffin cells incubated with 15 mM LiCl was found to increase by about mM after the intracellular Li + concentration reached a steady state. Therefore, once inside the cell, Li + is able to displace Mg 2+ from its binding sites.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Li
+
influx by bovine chromaffin cells, obtained from bovine adrenal medulla, was studied in intact cell suspensions using
7
Li NMR spectroscopy with the shift reagent Tm(HDOTP)
4-
. The influx rate ...constants, k
i
, were determined in the absence and in the presence of two Na
+
membrane transport inhibitors. The values obtained indicate that both voltage sensitive Na
+
channels and (Na
+
/K
+
)-ATPase play an important role in Li
+
uptake by these cells.
7
Li NMR T
1
and T
2
relaxation times for intracellular Li
+
in bovine chromaffin cells provided a T
1
/T
2
ratio of 305, showing that Li
+
is highly, immobilized due to strong binding to intracellular structures. Using fluorescence spectroscopy and the Mg
2+
fluorescent probe, furaptra, the free intracellular Mg
2+
concentration in the bovine chromaffin cells incubated with 15 mM LiCl was found to increase by about mM after the intracellular Li
+
concentration reached a steady state. Therefore, once inside the cell, Li
+
is able to displace Mg
2+
from its binding sites.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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