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. 1972 May;223(1):151–171. doi: 10.1113/jphysiol.1972.sp009839

The effect of voltage on the time course of end-plate currents

K L Magleby, C F Stevens
PMCID: PMC1331438  PMID: 4537943

Abstract

1. End-plate currents have been studied in glycerol-treated frog sartorius nerve—muscle preparations with the voltage clamp technique.

2. End-plate currents follow a simple exponential time course over most of their declining phase.

3. The rate constant α that characterizes this exponential decay depends upon membrane potential V according to the relationship α (V) = BeAV, with A = 0·00795 ± 0·00043 (S.E.) mV-1 and B = 1·67 ± 0·04 (S.E.) msec-1.

4. Voltage sensitivity decreases (that is, A in the above equation becomes smaller) as the recording and current-passing electrodes are moved away from the end-plate region.

5. The voltage sensitivity of α is decreased by decreasing the gain of the voltage clamp amplifier.

6. Changing the end-plate current amplitude by curare treatment, by increased calcium ion concentration, and by facilitation and depression has essentially no effect on end-plate current time course.

7. When membrane potential is changed step-wise during the decaying phase of the end-plate conductance change, currents begin to decline with a rate constant α appropriate to the new membrane potential in less than 0·2 msec.

8. Treatment with prostigmine methylsulphate in concentrations up to 50 μg/ml. slows end-plate current decay but has little effect on voltage sensitivity. That is, B in the above equation is decreased by prostigmine treatment, but A is relatively unaffected.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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