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A fluorescent indicator for measuring cytosolic free magnesium
1Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
The American Journal of Physiology
|March 1, 1989
Summary
A new fluorescent probe, FURAPTRA, allows measurement of intracellular ionized magnesium (Mg2+). This tool helps determine Mg2+ levels in cells, offering insights into cellular processes.
Area of Science:
- Biochemistry
- Cell Biology
- Analytical Chemistry
Background:
- O-aminophenol-N,N,O-triacetic acid (APTRA) is a known chelator.
- Intracellular ionized magnesium (Mg2+) plays crucial roles in cellular functions.
- Accurate measurement of intracellular Mg2+ is essential for understanding cell physiology.
Purpose of the Study:
- To develop a fluorescent analogue of APTRA for intracellular Mg2+ detection.
- To characterize the fluorescent properties and magnesium binding of the new probe.
- To measure cytosolic free Mg2+ concentration in isolated rat hepatocytes.
Main Methods:
- Modification of APTRA to create the fluorescent analogue FURAPTRA.
- Characterization of FURAPTRA's magnesium dissociation constant (Kd = 1.5 mM).
- Utilizing a ratio method, analogous to fura-2 for calcium, for Mg2+ measurements.
- Loading the acetoxymethyl form of FURAPTRA into isolated rat hepatocytes.
Main Results:
- FURAPTRA exhibits a fluorescence excitation shift upon magnesium complexation.
- Cytosolic free Mg2+ concentration in isolated rat hepatocytes was determined to be 0.59 mM.
- The high levels of cytosolic Mg2+ make ion buffering less problematic compared to calcium indicators.
Conclusions:
- FURAPTRA is a valuable fluorescent probe for intracellular ionized Mg2+ measurement.
- The development of FURAPTRA facilitates studies on cellular Mg2+ homeostasis.
- This probe offers advantages over existing methods due to reduced ion buffering issues.