Cusack N J, Hourani S M
Br J Pharmacol. 1981 Mar;72(3):443-7. doi: 10.1111/j.1476-5381.1981.tb10995.x.
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 microM) 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 E1 (PGE1)-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.
1 5'-N-乙基羧酰胺腺苷（NECA）是一种腺苷类似物，作为血管扩张剂，其效力比腺苷强22900倍。腺苷及其一些类似物也是人类血小板聚集的抑制剂。对NECA对人类血小板的作用进行了测试。2 NECA（1微摩尔）比腺苷更有效地抑制由5'-二磷酸腺苷（ADP）、肾上腺素、5-羟色胺（5-HT）和凝血酶诱导的人类血小板聚集。在抑制ADP和肾上腺素诱导的聚集方面，NECA的效力比腺苷强5至10倍。3 与腺苷一样，NECA引起血小板3',5'-环磷酸腺苷（环磷酸腺苷）水平的剂量依赖性增加，这被腺苷拮抗剂茶碱竞争性抑制。4 NECA的这些作用与腺苷的作用一样，具有完全的立体特异性，因为NECA的L-对映体没有活性。5 NECA不干扰ADP对前列腺素E1（PGE1）刺激的腺苷酸环化酶的抑制作用。6 NECA是迄今为止在人类血小板上测试的最有效的腺苷类似物，并且是5'修饰以保留对血小板腺苷受体亲和力的第一个例子。
