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Magnesium influx in dialyzed squid axons
The Journal of Membrane Biology
|October 19, 1978
Summary
Magnesium (Mg) influx into squid giant axons is regulated by internal sodium (Na) and adenosine triphosphate (ATP). Removing both significantly reduces Mg uptake, while their presence restores it to levels seen in intact axons.
Area of Science:
- Neuroscience
- Cell Physiology
- Biochemistry
Background:
- Magnesium is crucial for cellular functions.
- Understanding magnesium transport in neurons is vital for neuroscience research.
- Squid giant axons are a model system for studying ion transport.
Purpose of the Study:
- To quantify magnesium influx into squid giant axons.
- To investigate the roles of internal sodium and ATP in regulating Mg transport.
- To compare Mg flux in dialyzed axons with intact axons.
Main Methods:
- Dialysis of squid giant axons to control internal solute concentrations.
- Measurement of magnesium influx under varying internal Na and ATP conditions.
- Atomic absorption spectroscopy to determine Mg content.
Main Results:
- Mg influx was lowest (1 pmol/cm2 sec) when both Na and ATP were absent.
- Adding ATP increased Mg influx to 2.5 pmol/cm2 sec.
- Adding both Na and ATP resulted in Mg influx of 3 pmol/cm2 sec, matching intact axons.
- Axonal Mg content remained stable despite Li or Na seawater exposure.
Conclusions:
- Internal Na and ATP are key regulators of Mg influx in squid giant axons.
- Dialysis techniques allow for precise control and measurement of ion transport.
- These findings contribute to understanding neuronal Mg homeostasis.