An improved voltage clamp for gating current recording from the squid giant axon
Forster, I.C.; Greeff, N.G. (1995). An improved voltage clamp for gating current recording from the squid giant axon, in: Abbott, N.J. et al. (Ed.) Cephalopod neurobiology: neuroscience studies in squid, octopus and cuttlefish. pp. 97-106
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| Authors | | Top |
- Forster, I.C.
- Greeff, N.G.
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| Abstract |
The performance of the conventional cylindrical axon voltage clamp has been improved for high-resolution recording of gating currents from the squid giant axon. First, the requirement for fast, smooth settling of the membrane potential was met by applying a set of design equations derived from an analysis of an electrical model of the clamp. In practice, a membrane settling time down to 3 µs with up to 100 per cent compensation of the membrane series resistance was possible. Second, the overall instrumentation rms noise was reduced more than 10-fold by identifying the extrinsic noise sources and balancing their contributions against the intrinsic noise from the membrane. Third, instrumentation linearity was improved to reduce distortion of the early time course of gating currents such that this accounted for < 1 per cent of the total gating charge recorded. Gating current components with relaxations faster than 15 µs and slow components during sodium channel inactivation which were hitherto buried in the background noise have been detected with this system. |
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