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Ion flow through biomembranes. Physical theory explains its high sensitivity
1McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL 60208-3107.
Cell Biophysics
|February 1, 1992
Summary
Biomembranes show higher electrical potential sensitivity than predicted. Adsorbed calcium ions (Ca2+) rapidly gate ion channels, amplifying potential changes and explaining this phenomenon.
Area of Science:
- Biophysics
- Membrane Biology
- Ion Channel Physiology
Background:
- Biomembranes display electrical potential sensitivity exceeding classical Boltzmann relation predictions.
- The high sensitivity of some sodium channels (Na+) has remained unexplained.
Purpose of the Study:
- To explain the mechanism behind biomembranes' heightened sensitivity to electrical potential changes.
- To elucidate how adsorbed divalent cations influence ion channel gating and conductance.
Main Methods:
- Theoretical explanation using minimal mathematics.
- Analysis of the interaction between adsorbed Ca2+ and the electric field within ion channels.
Main Results:
- Adsorbed Ca2+ causes rapid channel gating, directly affecting conductance.
- This gating amplifies the potential change across the channel gate, exceeding membrane potential changes.
- A stochastic process provides the energy for this amplified response, consistent with the Boltzmann relation.
Conclusions:
- Adsorbed divalent cations provide a mechanism for enhanced biomembrane electrical sensitivity.
- This finding resolves the discrepancy between observed and predicted channel sensitivity.
- The study reconciles experimental observations with biophysical theory through a novel mechanism.