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The AC impedance of Necturus gallbladder epithelium
Pflugers Archiv : European Journal of Physiology
|November 14, 1978
Summary
The electrical impedance of Necturus gallbladder epithelium was analyzed. Findings reveal a simple electrical analogue representing the tissue, aiding in understanding cell membrane properties and epithelial function.
Area of Science:
- Physiology
- Biophysics
- Epithelial Transport
Background:
- Understanding the electrical properties of epithelial tissues is crucial for studying transport mechanisms.
- Necturus gallbladder serves as a model system for investigating epithelial cell function.
Purpose of the Study:
- To determine the electrical impedance of Necturus gallbladder epithelium across a range of frequencies.
- To develop an electrical analogue model for the gallbladder epithelium.
- To estimate the capacitances of the apical and basal cell membranes.
Main Methods:
- Impedance measurements using sine wave currents (1 Hz to 30 kHz).
- Analysis of impedance locus to fit an electrical analogue model.
- Voltage divider measurements with microelectrodes.
Main Results:
- The impedance locus showed a simple semicircle, representable by a parallel RC element in series with a resistor.
- An electrical analogue model consisting of 115 +/- 26 omega and 5.16 +/- 0.9 muF in parallel, in series with 5.3 +/- 1.3 omega, accurately described the epithelium.
- Estimated apical and basal cell membrane capacitances were approximately 7 and 18 muF/cm2, respectively.
Conclusions:
- The simple RC analogue is applicable to Necturus gallbladder epithelium under control conditions.
- The paracellular shunt and comparable apical/basal membrane time constants explain the observed impedance.
- Estimated cell membrane capacitances align with surface folding and known specific membrane capacitance values.