INTRACELLULAR PH MODULATES CYTOSOLIC FREE MAGNESIUM IN CULTURED CHICKEN HEART-CELLS

被引:44
作者
FREUDENRICH, CC
MURPHY, E
LEVY, LA
LONDON, RE
LIEBERMAN, M
机构
[1] DUKE UNIV, MED CTR, DEPT CELL BIOL, DIV PHYSIOL, BOX 3709, DURHAM, NC 27710 USA
[2] NIEHS, MOLEC BIOPHYS LAB, RES TRIANGLE PK, NC 27709 USA
来源
AMERICAN JOURNAL OF PHYSIOLOGY | 1992年 / 262卷 / 04期
关键词
HYDROGEN ION; IONIZED MAGNESIUM; CALCIUM; FLUORESCENT DYES;
D O I
10.1152/ajpcell.1992.262.4.C1024
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
To assess the role of pH in cellular Mg homeostasis, cytosolic pH (pH(i)) ws manipulated by the NH4Cl prepulse technique; pH(i), cytosolic Mg2+ (Mg(i)), and cytosolic Ca2+ (Ca(i)) 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: pH(i) = 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 pH(i) and were not secondary to changes in [Ca]i. The results suggest that pH(i) modulates Mg(i), probably by affecting cytosolic Mg binding and/or the transport of Mg across subcellular organelles.
引用
收藏
页码:C1024 / C1030
页数:7
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