Enhancement of the response to purinergic agonists in P2Y(1) transfected 1321N1 cells by antagonists suramin and PPADS
Enhancement of the response to purinergic agonists in P2Y(1) transfected 1321N1 cells by antagonists suramin and PPADS
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DOI：
10.1038/sj.bjp.0701010
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发表时间：
1997-03-01
影响因子：
7.3
通讯作者：
Boarder, MR
中科院分区：
文献类型：
--
作者：
Brown, CA;Charlton, SJ;Boarder, MR
1我们以前已经证明苏拉明和吡哆醛磷酸-6-偶氮苯基-2 '，4'二磺酸（PPADS）都是转染的P2 Y（1）受体的拮抗剂。在此，我们发现在一定的实验条件下，这两种P2拮抗剂可以增强对作用于这些受体的激动剂的反应。2在1321 N1人星形细胞瘤细胞中P2 Y（1）或P2 Y（2）受体的表达导致，在培养基的改变下，与不表达这些受体的细胞相比，[H-3]-肌醇（多）磷酸（[H-3]-InsP（x））的基础（未添加激动剂）积累升高。P2 Y（1）转染子中的这种升高比P2 Y（2）转染子中的这种升高大得多。3 PPADS和苏拉明都降低了表达P2 Y（1）的细胞中[H-3]-InsP（x）积累的这种基础水平。4当使用需要改变培养基的方案时，以使基础积累降低约50%的浓度加入拮抗剂，对浓度增加的2-甲硫基腺苷5 ′-三磷酸（2 MeSATP）有显著的刺激反应，在没有拮抗剂的情况下，激动剂没有显著的作用。5然而，当在没有更换培养基和没有拮抗剂存在的情况下加入2 MeSATP时，[3 H]-InsP（x）积累增加数倍。这些结果表明，内源性激动剂活性（可能是ATP/ADP）从表达P2 Y（1）的细胞中的释放可以产生这样的条件，其中对激动剂如2 MeSATP的应答只能在竞争性拮抗剂存在下才能看到。
1 We have previously shown that both suramin and pyridoxal-phosphate-6-azophenyl-2', 4' disulphonic acid (PPADS) act as antagonists at transfected P2Y(1) receptors. Here we show that under certain experimental conditions these two P2 antagonists can enhance the response to agonists acting at these receptors.2 The expression of either P2Y(1) or P2Y(2) receptors in 1321N1 human astrocytoma cells results, on a change of medium, in an elevation of basal (no added agonist) accumulation of [H-3]-inositol(poly)phosphates([H-3]-InsP(x)) compared to cells not expressing these receptors. This elevation is much greater in P2Y(1) transfectants than in P2Y(2) transfectants.3 Both PPADS and suramin reduced this basal level of [H-3]-InsP(x) accumulation in the P2Y(1) expressing cells.4 When a protocol was used which required changing the culture medium, antagonists were added at a concentration which reduced the basal accumulation by about 50%, there was a significant stimulation in response to increasing concentrations of 2-methylthioadenosine 5'-triphosphate (2MeSATP), in the absence of antagonists there was no significant effect of the agonist.5 However, when 2MeSATP was added in the absence of a change of medium and with no antagonist present, there was a several fold increase in [3H]-InsP(x) accumulation. These results show that a release of endogenous agonist activity (possibly ATP/ADP) from the P2Y(1) expressing cells can create conditions in which a response to an agonist such as 2MeSATP can only be seen in the presence of a competitive antagonist.