Evans R J, Lewis C, Buell G, Valera S, North R A, Surprenant A
Glaxo Institute for Molecular Biology, Geneva, Switzerland.
Mol Pharmacol. 1995 Aug;48(2):178-83.
cDNAs encoding P2x purinoceptors from human bladder smooth muscle and from rat PC-12 cells were expressed in oocytes and human embryonic kidney 293 cells. Agonist potencies of 2-methylthio-ATP = 2-chloro-ATP = ATP > = 2'- and 3'-O-(4-benzoylbenzoyl)-ATP > or = adenosine-5'-O-(3-thio)-triphosphate > or = P1,P5-di(adenosine-5') pentaphosphate >> ADP prevailed for both P2x purinoceptors. There were two main differences in agonist sensitivity between the two receptors. First, ATP was 10 times more potent at the receptor from bladder (EC50, 0.8 microM) than at the receptor from PC-12 cells (EC50, 8.2 microM). Second, alpha,beta-methylene-ATP and L- and D-beta,gamma-methylene-ATP were agonists in cells expressing the bladder smooth muscle receptor (EC50, 1-3 microM) but were ineffective in cells expressing the PC-12 receptor. The P2 purinoceptor antagonists suramin, pyridoxal phosphate 6-azophenyl-2',4'-disulfonic acid, and pyridoxal-5-phosphate acted similarly at both receptor forms, producing noncompetitive inhibition, with IC50 values of 1-5 microM for suramin and pyridoxal phosphate 6-azophenyl-2',4'-disulfonic acid and 10-20 microM for pyridoxal-5-phosphate. 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid distinguished receptor subtypes, producing potent inhibition of the bladder smooth muscle P2x-mediated response, with an IC50 value of 3 microM; it inhibited the PC-12 form by < 40% at 100 or 300 microM. This study thus defines the pharmacological properties of homo-oligomeric forms of these two types of cloned P2x receptor channels.
编码来自人膀胱平滑肌和大鼠嗜铬细胞瘤PC - 12细胞P2X嘌呤受体的cDNA在卵母细胞和人胚肾293细胞中表达。对于两种P2X嘌呤受体，激动剂效力顺序为：2 - 甲硫基 - ATP = 2 - 氯 - ATP = ATP >= 2'-和3'-O-(4 - 苯甲酰苯甲酰基)-ATP >= 腺苷 - 5'-O-(3 - 硫代)-三磷酸 >= P1,P5 - 二(腺苷 - 5')五磷酸 >> ADP。两种受体在激动剂敏感性上有两个主要差异。第一，ATP对膀胱受体（EC50，0.8 microM）的效力比对PC - 12细胞受体（EC50，8.2 microM）高10倍。第二，α,β - 亚甲基 - ATP以及L - 和D - β,γ - 亚甲基 - ATP在表达膀胱平滑肌受体的细胞中是激动剂（EC50，1 - 3 microM），但在表达PC - 12受体的细胞中无作用。P2嘌呤受体拮抗剂苏拉明、磷酸吡哆醛6 - 偶氮苯基 - 2',4'-二磺酸和磷酸吡哆醛对两种受体形式作用相似，产生非竞争性抑制，苏拉明和磷酸吡哆醛6 - 偶氮苯基 - 2',4'-二磺酸的IC50值为1 - 5 microM，磷酸吡哆醛为10 - 20 microM。4,4'-二异硫氰酸根合芪 - 2,2'-二磺酸可区分受体亚型，对膀胱平滑肌P2X介导的反应有强效抑制作用，IC50值为3 microM；在100或300 microM时对PC - 12形式的抑制小于40%。因此，本研究确定了这两种克隆的P2X受体通道同型寡聚体形式的药理学特性。
