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Updated: Jun 25, 2026
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Preparation of Synaptic Plasma Membrane and Postsynaptic Density Proteins Using a Discontinuous Sucrose Gradient
Published on: September 3, 2014
Origin of axon membrane hyperpolarization under sucrose-gap
1Bureau of Medicine and Surgery, Navy Department, United States Naval Medical Research Institute, Bethesda, Maryland, USA.
Biophysical Journal
|February 13, 2009
Summary
The sucrose-gap method causes membrane hyperpolarization due to junction potentials. Replacing chloride with low-mobility anions in seawater eliminates this artifact, revealing true membrane potentials.
Area of Science:
- Neuroscience
- Biophysics
Background:
- The sucrose-gap method is used to measure membrane potentials.
- This method can induce artificial hyperpolarization compared to intracellular recordings.
Purpose of the Study:
- To evaluate the contribution of sucrose-seawater junction potential to hyperpolarization.
- To identify methods for eliminating sucrose-gap-induced artifacts.
Main Methods:
- Used sucrose-gap and microelectrode techniques on lobster giant axons.
- Performed anion and cation substitutions in artificial seawater.
- Measured resting membrane potential and liquid junction potential.
Main Results:
- A significant liquid junction potential exists between sucrose and artificial seawater.
- Junction potential and hyperpolarization varied with ion substitutions.
- Replacing chloride with low-mobility anions eliminated junction potential and hyperpolarization.
Conclusions:
- Loop currents at sucrose-seawater-axon junctions contribute to hyperpolarization.
- Low-mobility anions can mitigate sucrose-gap artifacts for accurate membrane potential measurement.
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