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THE RELEASE OF LABELLED ACETYLCHOLINE AND CHOLINE FROM CEREBRAL CORTICAL SLICES STIMULATED ELECTRICALLY
Author(s) -
RICHARDSON I.W.,
SZERB J.C.
Publication year - 1974
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1974.tb09717.x
Subject(s) - acetylcholine , choline , neuroscience , cerebral cortex , chemistry , electric stimulation , medicine , stimulation , biology , endocrinology , biochemistry
1 In order to establish the origin of the increased efflux of radioactivity caused by electrical stimulation of cerebral cortical slices which had been incubated with [ 3 H]‐choline, labelled choline and acetylcholine (ACh) collected by superfusion were separated by gold precipitation. 2 In the presence of physostigmine electrical stimulation (1 Hz, 10 min) increased the release of only [ 3 H]‐ACh which was greatly enhanced by the addition of atropine. 3 Continuous stimulation in the presence of physostigmine resulted in an evoked release of [ 3 H]‐ACh which declined asymptotically. This evoked release appeared to follow first‐order kinetics with a rate constant which remained stable over the course of prolonged stimulation. 4 The rate constant for the evoked release of [ 3 H]‐ACh with 1 Hz stimulation was three times greater in the presence of physostigmine and atropine than in the presence of physostigmine alone, while the size of the store from which [ 3 H]‐ACh was released was nearly identical under these two conditions. 5 In the absence of physostigmine and atropine, stimulation caused the appearance of only [ 3 H]‐choline in the samples. 6 Reduction of [ 3 H]‐ACh stores before the application of physostigmine resulted in a reduced evoked release of total radioactivity, both in the absence or presence of physostigmine and atropine, and decreased the evoked release of [ 3 H]‐ACh without affecting the release of [ 3 H]‐choline. 7 Results suggest that electrical stimulation of cortical slices which had been incubated with [ 3 H]‐choline causes the release of only [ 3 H]‐ACh, both in the presence or absence of an anticholinesterase. The evoked increase in the efflux of total radioactivity is therefore a good measure of the release of [ 3 H]‐ACh.