Shinozuka K, Bjur R A, Westfall D P
Department of Pharmacology, University of Nevada School of Medicine, Reno 89557.
Naunyn Schmiedebergs Arch Pharmacol. 1988 Sep;338(3):221-7. doi: 10.1007/BF00173391.
The effects of a number of purinoceptor agents on the release of endogenous noradrenaline from the electrically stimulated rat caudal artery were determined. Noradrenaline was quantified by high performance liquid chromatography-electrochemical detection techniques. Both P1-receptor and P2-receptor agonists reduced the release of noradrenaline; the relative order of potency being 2-chloroadenosine greater than beta, gamma methylene ATP greater than ATP greater than or equal to adenosine. The adenosine uptake inhibitor S-p-nitro-benzyl-6-thioguanosine potentiated the effects of adenosine but not those of the adenine nucleotides. This suggests that the nucleotides do not need to be converted to adenosine to produce a prejunctional inhibition of the release of noradrenaline. The P1-receptor antagonist 8-(p-sulfophenyl) theophylline reduced the inhibitory effects of both P1- and P2-receptor agonists as did the photolysis of tissues with an intense light source. The findings indicate that prejunctional purinoceptors that mediate an inhibition of the release of noradrenaline from the adrenergic nerves of the caudal artery may not be adequately defined as either P1- or P2-receptors and thus appear to represent a unique receptor. We suggest referring to these receptors as P3-purinoceptors.
测定了多种嘌呤受体激动剂对电刺激大鼠尾动脉内源性去甲肾上腺素释放的影响。采用高效液相色谱 - 电化学检测技术对去甲肾上腺素进行定量分析。P1受体和P2受体激动剂均能减少去甲肾上腺素的释放；其效价相对顺序为2 - 氯腺苷＞β,γ - 亚甲基ATP＞ATP≥腺苷。腺苷摄取抑制剂S - p - 硝基苄基 - 6 - 硫代鸟苷增强了腺苷的作用，但对腺嘌呤核苷酸的作用无增强效果。这表明核苷酸无需转化为腺苷即可对去甲肾上腺素释放产生突触前抑制作用。P1受体拮抗剂8 -（对 - 磺基苯基）茶碱以及用强光照射组织均能降低P1和P2受体激动剂的抑制作用。这些研究结果表明，介导尾动脉肾上腺素能神经去甲肾上腺素释放抑制作用的突触前嘌呤受体可能无法简单地归为P1或P2受体，因此似乎代表一种独特的受体。我们建议将这些受体称为P3嘌呤受体。
