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. 1970 Jan;206(1):61–71. doi: 10.1113/jphysiol.1970.sp008997

Effect of calcium on excitatory neuromuscular transmission in the crayfish

H Bracho, R K Orkand
PMCID: PMC1348586  PMID: 5498460

Abstract

1. The effects of varying the external Ca concentration from 1·8 to 30 mM/l. (⅛-2 times normal) have been studied at the in vitro crayfish excitatory neuromuscular junction. Electrophysiological techniques were used to record transmembrane junctional potentials from muscle fibres and extracellular junctional currents from the vicinity of nerve terminals.

2. The excitatory junctional potential amplitude was proportional to [Ca]0n, where n varied between 0·68 and 0·94 (mean 0·82) when [Ca]0 was varied from 1·8 to 15 mM/l.

3. The increase in junctional potential amplitude on raising [Ca]0 resulted primarily from an increase in the average number of quanta of excitatory transmitter released from the presynaptic nerve terminal by the nerve impulse.

4. The size of the quanta, synaptic delay, presynaptic potential and electrical properties of the muscle membrane were little affected by changes in calcium concentration in the range studied.

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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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