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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1975 Nov;72(11):4371–4375. doi: 10.1073/pnas.72.11.4371

Acetylcholine-receptor-mediated ion flux in electroplax membrane preparations.

G P Hess, J P Andrews, G E Struve, S E Goombs
PMCID: PMC388723  PMID: 1060114

Abstract

The kinetics of acetylcholine-receptor-mediated sodium efflux from electroplax microsacs of electrophorus electricus has been analyzed. This led to the discovery that only a small fraction of the observed efflux is affected by chemical effectors such as carbamylcholine. Experimental conditions were chosen so that the receptor-mediated flux could be analyzed without the measurements' being obscured by efflux from the nonexcitable microsacs. Near equilibrium the efflux follows a single exponential decay. The apparent first order rate constant for sodium-22 efflux was determined as a function of effector concentration and is considerably higher than previously estimated. The process does not show cooperativity under the experimental conditions, in agreement with the binding isotherms of effectors and the same membrane preparation. The presence of potassium ions inhibits the receptor-mediated sodium flux. It is suggested that interaction of inorganic ions with the receptor may play an important role in the cooperative effects observed in electrophysiological experiments.

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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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