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Chloramine-T alters the nerve membrane birefringence response
1Department of Physiology and Biophysics, University of Miami School of Medicine, Florida 33101.
The Journal of Membrane Biology
|February 1, 1990
Summary
Birefringence changes in squid axons show fast and slow phases during voltage changes. Chloramine-T selectively removes the slow phase, suggesting its link to sodium channel inactivation.
Area of Science:
- Neuroscience
- Biophysics
- Cellular Physiology
Background:
- Birefringence changes reflect molecular rearrangements in nerve membranes.
- Voltage-clamp studies are crucial for understanding ion channel dynamics.
Purpose of the Study:
- To characterize the biphasic birefringence response in squid giant axons during voltage-clamp pulses.
- To investigate the molecular basis of the fast and slow phases of the birefringence response.
Main Methods:
- Internal perfusion of squid giant axons.
- Depolarizing voltage-clamp pulses.
- Optical measurement of birefringence changes.
- Application of chloramine-T and anesthetics.
Main Results:
- A biphasic birefringence response (fast and slow phases) was observed during depolarizing pulses.
- The slow phase was dependent on depolarization magnitude and was abolished by chloramine-T.
- Chloramine-T treatment also affected the recovery phases and normalized the fast 'on' and 'off' responses.
- Anesthetics reduced the overall birefringence response by approximately 20%.
Conclusions:
- The slow phase of the birefringence response is linked to sodium current inactivation.
- A rocking helix model can explain the observed birefringence changes and gating current data.