Koizumi S, Inoue K
Division of Pharmacology, National Institute of Health Sciences, Tokyo, Japan.
Br J Pharmacol. 1997 Sep;122(1):51-8. doi: 10.1038/sj.bjp.0701344.
1 The effect of adenosine 5'-triphosphate (ATP) on glutamatergic synaptic transmission in hippocampus was examined by an indicator of intracellular Ca2+ oscillations. These oscillations were postsynaptic responses by glutamate released from presynaptic sites. ATP completely inhibited the oscillations in a concentration-dependent manner. 2 The ATP-induced inhibition was mediated via P2-purinoceptors since ATP exhibited the inhibitory action even in the presence of P1-purinoceptor antagonists. Also non-hydrolysable ATP analogues and uridine 5'-triphosphate (UTP) inhibited the oscillation. 3 The rank order of agonist potency of ATP analogues for inhibition of the Ca2+ oscillation was as follows: 2-methyl-thio-adenosine 5'-triphosphate > or = ATP > adenosine 5'-O-(3-thiotriphosphate)>UTP> alpha, beta-methylene-adenosine 5'-triphosphate. These inhibitory effects were insensitive to suramin. Judging from this rank order of potency, the inhibitory P2-purinoceptor could be assigned to a subclass of GTP-binding protein coupled-type receptors. 4 The site of action of ATP was thought to be presynaptic since ATP did not affect the postsynaptic Ca2+ responses by glutamate. These results suggest the existence of a presynaptic inhibitory P2-receptor that inhibits glutamate release in the hippocampus.
1 通过细胞内Ca2+振荡指标研究了5'-三磷酸腺苷（ATP）对海马谷氨酸能突触传递的影响。这些振荡是突触前位点释放的谷氨酸引起的突触后反应。ATP以浓度依赖性方式完全抑制了振荡。2 ATP诱导的抑制作用是通过P2嘌呤受体介导的，因为即使存在P1嘌呤受体拮抗剂，ATP仍表现出抑制作用。此外，不可水解的ATP类似物和5'-三磷酸尿苷（UTP）也抑制了振荡。3 ATP类似物抑制Ca2+振荡的激动剂效力排序如下：2-甲基硫代-5'-三磷酸腺苷≥ATP＞5'-O-(3-硫代三磷酸)腺苷＞UTP＞α,β-亚甲基-5'-三磷酸腺苷。这些抑制作用对苏拉明不敏感。根据这种效力排序判断，抑制性P2嘌呤受体可归为GTP结合蛋白偶联型受体的一个亚类。4 ATP的作用位点被认为是突触前的，因为ATP不影响谷氨酸引起的突触后Ca2+反应。这些结果表明海马中存在一种抑制谷氨酸释放的突触前抑制性P2受体。
