Summary
Impedance data from squid giant axons reveal a lossy membrane capacity of 1 muF/cm2. Additional data, previously excluded, confirm Schwann cell sheath properties, supporting current clamp and electron microscope findings.
Area of Science:
- Neuroscience
- Biophysics
Background:
- Early impedance studies on squid giant axons provided initial membrane capacity values.
- Some experimental data were previously excluded due to complexity.
Purpose of the Study:
- To re-evaluate previously excluded impedance data from squid giant axons.
- To ascribe these data to the Schwann cell sheath and provide independent confirmation.
Main Methods:
- Analysis of impedance data from squid giant axon experiments up to 5 MHz.
- Comparison with recent current clamp and electron microscope findings.
Main Results:
- A lossy membrane capacity of 1 muF/cm2 was determined between 1-200 kHz.
- Fragmentary data up to 5 MHz were ascribed to the Schwann cell sheath, yielding 1.6 omega-cm2 and 12.5 membrane layers.
Conclusions:
- The re-evaluated impedance data support and independently confirm recent findings on squid giant axon membrane properties.
- The Schwann cell sheath contributes significantly to the overall impedance characteristics.
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