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THE VARIATION OF ELECTRICAL RESISTANCE WITH APPLIED POTENTIAL : I. INTACT VALONIA VENTRICOSA
1Laboratories of The Rockefeller Institute for Medical Research.
The Journal of General Physiology
|October 30, 2009
Summary
The electrical resistance of Valonia ventricosa cells varies with applied direct current potential. Resistance increases significantly at higher potentials, potentially due to ion movement within the cell.
Area of Science:
- Cell biology
- Biophysics
Background:
- Valonia ventricosa cells exhibit variable electrical resistance.
- This resistance is dependent on the applied direct current potential.
Purpose of the Study:
- To investigate the variability of electrical resistance in Valonia ventricosa cells.
- To understand the factors influencing resistance changes, such as applied potential and ion movement.
Main Methods:
- Measurements of direct current resistance in freshly gathered Valonia ventricosa cells.
- Application of varying electrical potentials to observe resistance changes.
- Challenging one end of the cell to determine current direction effects.
- Observation of resistance changes over time as cells stabilize in laboratory conditions.
Main Results:
- Cell resistance is low at low applied potentials and rises sharply at higher potentials (over 100% increase in whole cell, several hundred percent in protoplasm).
- Resistance stabilizes in a constant state after cells stand in the lab, reaching a maximum below breakdown potential (~100 mV).
- During the variable state, resistance increases with positive current entering the protoplasm and decreases with current exiting the vacuole.
Conclusions:
- The observed resistance changes are linked to ion dynamics within the protoplasm, possibly involving potassium ions.
- A significant portion of the apparent resistance rise may be attributed to a back electromotive force (EMF) generated by current flow.
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