The Adenosine Receptor Agonist,APNEA, Increases Calcium Influx into Rat Cortical Synaptosomes through N-Type Channels Associated with A2a Receptors |
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Authors: | Li Sheng-Nan Wong Peter T-H |
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Institution: | (1) Department of Pharmacology, Faculty of Medicine, National University of Singapore, 10 Kent Ridge, Singapore, 119620;(2) Department of Pharmacology, Faculty of Medicine, National University of Singapore, 10 Kent Ridge, Singapore, 119620 |
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Abstract: | N6-2-(4-aminophenyl)ethyladenosine (APNEA) is a nonselective adenosine receptor agonist known to have a high affinity for the adenosine A1 and A3 receptors. It was found to be able to dose-dependently increase the sustained (4 min) Ca2+ influx into rat cortical synaptosomes while 2-chloro-N6-(3-iodobenzyl)-adenosine-5-N-methyluronamide (Cl-IB-MECA), a selective A3 agonist has no effect. However, this effect of APNEA was not affected by the presence of 8-cyclopentyl-l,3-dimethylxanthine (CPT), a selective A1 antagonist; but instead completely abolished by 8-(3-chlorostyryl)caffeine (CSC), a selective A2a antagonist, or -conotoxin GVIA. These results show that in the rat cortex, presynaptic A2a receptors can mediate neurotransmitter release by increasing Ca2+ influx through the N-type calcium channels. A1 and A3 receptors appear not to be involved. |
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Keywords: | Calcium influx adenosine receptors APNEA N-type calcium channels rat cortex |
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