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Adenosine Receptor Agonists Inhibit K + ‐Evoked Ca 2+ Uptake by Rat Brain Cortical Synaptosomes
Author(s) -
Wu P. H.,
Phillis J. W.,
Thierry D. L.
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb07949.x
Subject(s) - adenosine , extracellular , adenosine receptor , adenosine receptor antagonist , chemistry , adenosine a1 receptor , receptor , medicine , depolarization , synaptosome , neurotransmitter , endocrinology , receptor antagonist , purinergic signalling , antagonist , biochemistry , biology , agonist , in vitro
The uptake of Ca 2+ by a K + ‐depolarized rat brain cerebral cortical crude synaptosomal preparation (P 2 fraction) was investigated. The characteristics of the Ca 2+ uptake system are similar to those observed by other investigators. The preparation is also a suitable model with which to study the effects of adenosine on Ca 2+ uptake and neurotransmitter release, as it is generally accepted that K + ‐evoked Ca 2+ uptake is intimately related to depolarization‐induced release of neurotransmitters. We have demonstrated that an extracellular receptor is involved in mediating the adenosine‐evoked inhibition of K + ‐evoked Ca 2+ uptake. The pharmacological properties of the receptor suggest that it may be similar in some respects to the A 2 ‐receptor associated with adenylate cyclase. The adenosine uptake inhibitor, dipyridamole, potentiated the action of adenosine, suggesting that re‐uptake is important in controlling the extracellular adenosine concentration and thus in the regulation of the adenosine receptor. The adenosine receptor antagonist theophylline inhibited the effects of adenosine. Calmodulin inhibited K + ‐ evoked uptake of Ca 2+ by the synaptosomal fraction.