King B F, Ziganshina L E, Pintor J, Burnstock G
Department of Anatomy and Developmental Biology, University College London.
Br J Pharmacol. 1996 Apr;117(7):1371-3. doi: 10.1111/j.1476-5381.1996.tb15293.x.
A full pharmacological characterization was carried out on a recombinant ATP-gated ion channel (P2X2 purinoceptor) expressed in Xenopus oocytes. This slowly-desensitizing neuronal P2X2 purinoceptor, activated by ATP (EC50 = 4.6 +/- 1 microM at pH 7.4; n = 4), showed the agonist potency order: ATP > or = 2-MeSATP = ATP gamma S > or = ATP alpha S > > Bz-ATP. The receptor affinity for ATP was enhanced 5-10 fold by acidifying the bathing solution (to pH 6.5) but was diminished 4-5 fold in an alkaline solution (pH 8.0). The maximum activity of P2X2 purinoceptors and the activity order of a series of nucleotides were unaltered by changing extracellular pH. Interestingly, ATP sensitivity at a recombinant P2Y1 purinoceptor remained unaltered with changing extracellular pH. These results indicate that acidotic conditions in the synaptic cleft could strengthen purinergic transmission at neuronal P2X2 purinoceptors.
对非洲爪蟾卵母细胞中表达的重组ATP门控离子通道（P2X2嘌呤能受体）进行了全面的药理学特性分析。这种缓慢脱敏的神经元P2X2嘌呤能受体由ATP激活（在pH 7.4时，EC50 = 4.6 +/- 1 microM；n = 4），显示出激动剂效力顺序：ATP > 或 = 2-MeSATP = ATPγS > 或 = ATPαS > > Bz-ATP。通过酸化浴液（至pH 6.5），受体对ATP的亲和力提高了5至10倍，但在碱性溶液（pH 8.0）中降低了4至5倍。改变细胞外pH值不会改变P2X2嘌呤能受体的最大活性以及一系列核苷酸的活性顺序。有趣的是，重组P2Y1嘌呤能受体的ATP敏感性不会随细胞外pH值的变化而改变。这些结果表明，突触间隙中的酸中毒条件可增强神经元P2X2嘌呤能受体处的嘌呤能传递。
