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5′‐N‐ETHYLCARBOXAMIDOADENOSINE: A POTENT INHIBITOR OF HUMAN PLATELET AGGREGATION
Author(s) -
CUSACK N.J.,
HOURANI S.M.O.
Publication year - 1981
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.1476-5381.1981.tb10995.x
Subject(s) - adenosine , adenosine receptor , platelet , chemistry , adenosine a3 receptor , purinergic signalling , endocrinology , medicine , adenosine receptor antagonist , theophylline , adenylate kinase , adenosine diphosphate , adenosine monophosphate , pharmacology , receptor , biochemistry , biology , agonist , platelet aggregation
1 5′‐N‐ethylcarboxamidoadenosine (NECA) is an adenosine analogue which is 22,900 times more potent than adenosine as a vasodilator. Adenosine and some of its analogues are also inhibitors of human platelet aggregation. NECA was tested for its effects on human platelets. 2 NECA (1 μ m ) inhibited human platelet aggregation induced by adenosine 5′‐diphosphate (ADP), adrenaline, 5‐hydroxytryptamine (5‐HT) and thrombin more powerfully than adenosine. NECA was 5 to 10 times more potent than adenosine at inhibiting ADP‐ and adrenaline‐induced aggregation. 3 NECA, like adenosine, caused dose‐dependent increases in levels of platelet adenosine 3′,5′‐cyclic monophosphate (cyclic AMP), which were competitively inhibited by theophylline, an adenosine antagonist. 4 These effects of NECA, like those of adenosine, were completely stereospecific as the l ‐enantiomer of NECA was inactive. 5 NECA did not interfere with the inhibition by ADP of prostaglandin E 1 (PGE 1 )‐stimulated adenylate cyclase. 6 NECA is the most potent analogue of adenosine tested so far on human platelets, and is the first example of a 5′ modification to retain affinity for the platelet adenosine receptor.