The adenosine receptor agonist, APNEA, increases calcium influx into rat cortical synaptosomes through N-type channels associated with A2a receptors.
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-1,3-dimethylxanthine (CPT), a selective A1 antagonist; but instead completely abolished by 8-(3-chlorostyryl)caffeine (CSC), a selective A2a antagonist, or omega-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.
Li
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Department of Pharmacology, Faculty of Medicine, National University of Singapore.
Wong
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PT
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001923:Brain Chemistry; D002110:Caffeine / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020864:Calcium Channels, N-Type / Q000187:drug effects / Q000378:metabolism*; D002540:Cerebral Cortex / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D008297:Male; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D043705:Receptor, Adenosine A2A; D043684:Receptor, Adenosine A3; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism; D014970:Xanthines / Q000494:pharmacology; D020866:omega-Conotoxin GVIA / Q000494:pharmacology
C112774:1,3-dimethyl-8-cyclopentylxanthine; D002121:Calcium Channel Blockers; D020864:Calcium Channels, N-Type; C086112:N(6)-2-(4-aminophenyl)ethyladenosine; D058906:Purinergic P1 Receptor Agonists; D058915:Purinergic P1 Receptor Antagonists; D043705:Receptor, Adenosine A2A; D043684:Receptor, Adenosine A3; D018047:Receptors, Purinergic P1; D014970:Xanthines; C081320:8-(3-chlorostyryl)caffeine; D002110:Caffeine; D020866:omega-Conotoxin GVIA; D000241:Adenosine; D002118:Calcium; C090034:2-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide