Buckle P J, Spence I
Naunyn Schmiedebergs Arch Pharmacol. 1982 May;319(2):130-5. doi: 10.1007/BF00503925.
The actions of the nucleosides adenosine, 1-methyladenosine, 1-methylisoguanosine and 2-chloradenosine on transmitter release at the mammalian neuromuscular junction and the vas deferens have been examined. All the nucleosides depressed the evoked release of acetylcholine at the neuromuscular junction, the order of potency being 2-chloroadenosine greater than 1-methylisoguanosine greater than 1-methyladenosine much greater than adenosine. This correlated reasonably with the potency of these compounds in depressing spinal reflexes in anaesthetized mice (Buckle and Spence 1981). Neither adenosine (0.5 and 1.0 mmol l-1) or 1-methylisoguanosine (10 and 20 mumol l-1) had any effect on the elevation of minature endplate potential frequency caused by 12 mmol l-1 K+ at the neuromuscular junction. In the guinea-pig vas deferens, however, 1-methylisoguanosine and adenosine were approximately equipotent in depressing overflow of radioactively labelled noradrenaline. The actions of the nucleosides have been compared with their effects on adenylate cyclase and their ability to resist uptake and deamination. It is concluded that the relative potencies of the nucleosides are not determined solely by their ability to survive in the extracellular fluid.
已对核苷腺苷、1-甲基腺苷、1-甲基异鸟苷和2-氯腺苷对哺乳动物神经肌肉接头和输精管递质释放的作用进行了研究。所有核苷均抑制神经肌肉接头处乙酰胆碱的诱发释放，其效力顺序为2-氯腺苷大于1-甲基异鸟苷大于1-甲基腺苷远大于腺苷。这与这些化合物在抑制麻醉小鼠脊髓反射中的效力合理相关（Buckle和Spence，1981年）。腺苷（0.5和1.0 mmol l-1）或1-甲基异鸟苷（10和20 μmol l-1）对神经肌肉接头处由12 mmol l-1 K+引起的微小终板电位频率升高均无影响。然而，在豚鼠输精管中，1-甲基异鸟苷和腺苷在抑制放射性标记去甲肾上腺素的溢出方面效力大致相当。已将这些核苷的作用与其对腺苷酸环化酶的影响以及它们抵抗摄取和脱氨的能力进行了比较。得出的结论是，核苷的相对效力并非仅由其在细胞外液中的存活能力决定。
