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To assess the role of pH in cellular Mg homeostasis, cytosolic pH (pHi) was manipulated by the NH4Cl prepulse technique; pHi, cytosolic Mg2+ (Mgi), and cytosolic Ca2+ (Cai) were measured fluorometrically in single cultured embryonic chicken heart cells loaded with 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF), FURAPTRA, and fura-2, respectively. The basal values obtained were as follows: pHi = 7.21 +/- 0.10 (n = 7), [Mg]i = 0.51 +/- 0.08 mM (n = 9), [Ca]i = 126 +/- 15 nM (n = 7). When cells were perfused with 10 mM NH4Cl solution for 5 min, a transient alkalinization (0.53 U) of the cytosol was accompanied by a transient decrease (0.12 mM) in [Mg]i and a transient increase (59 nM) in [Ca]i; these changes approached control levels within 5 min. Upon removal of NH4Cl, a transient acidification (0.89 U) of the cytosol was accompanied by a transient increase (0.10 mM) in [Mg]i and a transient increase (125 nM) in [Ca]i; again, these changes returned toward control levels within 5 min. No significant changes in total cell Mg or Ca were observed during these manipulations. NH4Cl-evoked changes in [Mg]i were not altered significantly by either Mg-free or Ca-free conditions. Changes in [Mg]i were inversely correlated with changes in pHi and were not secondary to changes in [Ca]i. The results suggest that pHi modulates Mgi, probably by affecting cytosolic Mg binding and/or the transport of Mg across subcellular organelles.
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
July 1989,
The American journal of physiology,
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
February 1993,
The American journal of physiology,
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
April 1989,
The Journal of biological chemistry,
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
February 1992,
Endocrinology,
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
February 2002,
Cardiovascular research,
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
June 1990,
Experimental cell research,
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
August 1991,
European journal of pharmacology,
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
January 1988,
Journal of molecular and cellular cardiology,
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
February 1989,
The American journal of physiology,
C C Freudenrich, and
E Murphy, and
L A Levy, and
R E London, and
M Lieberman
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