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Magnesium homeostasis in cardiac cells
C C Freudenrich1, E Murphy, S Liu
1Department of Cell Biology, Duke University Medical Center, Durham, NC 27710.
Molecular and Cellular Biochemistry
|September 8, 1992
Summary
Investigating magnesium (Mg2+) homeostasis in chicken heart cells revealed that calcium (Ca2+) can modulate intracellular Mg2+ levels. Intracellular pH (pHi) also inversely affects Mg2+ concentration, suggesting complex interactions in cellular ion regulation.
Area of Science:
- Cardiology
- Cell Physiology
- Biochemistry
Background:
- Magnesium (Mg2+) is crucial for cellular function.
- Understanding Mg2+ homeostasis is vital for cardiac health.
- Previous research suggested a Na/Mg exchange mechanism in heart cells.
Purpose of the Study:
- To investigate Mg2+ homeostasis in cultured chicken heart cells.
- To determine if a Na/Mg exchange mechanism regulates cytosolic Mg2+ ([Mg2+]i).
- To explore the influence of calcium (Ca2+) and intracellular pH (pHi) on [Mg2+]i.
Main Methods:
- Utilized the fluorescent Mg2+ indicator FURAPTRA to measure [Mg2+]i.
- Manipulated extracellular and intracellular sodium (Na+) gradients.
- Employed pH-sensitive microelectrodes and the BCECF indicator to measure pHi.
- Used the NH4Cl prepulse method to alter pHi.
Main Results:
- Extracellular Na+ removal increased [Mg2+]i, an effect attenuated by Ca2+ removal.
- Raising intracellular Na+ with ouabain also increased [Mg2+]i in a Ca2+-dependent manner.
- Decreased pHi was observed upon extracellular Na+ removal, suggesting Ca2+ and H+ interaction.
- NH4Cl-induced changes in pHi showed an inverse relationship with [Mg2+]i ([Mg2+]i changed by -0.16 mM/unit pH).
Conclusions:
- Evidence for Na/Mg exchange in chicken heart cells was not found.
- Calcium (Ca2+) can modulate intracellular Mg2+ concentration ([Mg2+]i).
- Intracellular pH (pHi) inversely affects [Mg2+]i, indicating a significant interaction between pH and Mg2+ regulation.