豚鼠离体盲肠带的嘌呤受体
The purinoceptors of the guinea-pig isolated taenia caeci.
作者信息
Piper A S, Hollingsworth M
机构信息
Smooth Muscle Pharmacology Group, School of Biological Sciences, University of Manchester, UK.
出版信息
Eur J Pharmacol. 1995 Jul 4;280(2):125-34. doi: 10.1016/0014-2999(95)00182-k.
The guinea-pig taenia caeci contains both P1 and P2 purinoceptors mediating relaxation. The P2 purinoceptors have been further characterized using an experimental approach designed to minimise complicating factors. In the presence of the adenosine uptake inhibitor S-(4-nitrobenzyl)-6-thioinosine (NBTI, 300 nM) and a pA100 concentration of the P1 purinoceptor antagonist 8-sulphophenyltheophylline (140 microM), the potency order of agonists was: 2-methylthio-ATP >> adenosine 5'-triphosphate (ATP) = alpha, beta-methylene ATP > beta, gamma-methylene ATP >> uridine 5'-triphosphate. Suramin antagonized ATP (pA2 = 5.52 +/- 0.17, Schild plot slope = 0.67 +/- 0.08) and 2-methylthio-ATP (pA2 = 5.78 +/- 0.30, Schild plot slope = 1.37 +/- 0.39) while responses to 5'-N-ethylcarboxamidoadenosine (NECA) were unaffected. The findings suggest that suramin, while it is selective for P2 relative to P1 purinoceptors, is not a true competitive antagonist. Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) antagonized ATP in isolated guinea-pig vas deferens, but had no effect on responses to ATP in guinea-pig taenia caeci indicating it is selective for P2X relative to P2Y purinoceptors.
豚鼠盲肠带中含有介导舒张作用的P1和P2嘌呤受体。使用旨在最小化复杂因素的实验方法对P2嘌呤受体进行了进一步的特性研究。在腺苷摄取抑制剂S-(4-硝基苄基)-6-硫代肌苷（NBTI，300 nM）和P1嘌呤受体拮抗剂8-磺基苯基茶碱（140 microM）的pA100浓度存在下，激动剂的效价顺序为：2-甲硫基-ATP >> 腺苷5'-三磷酸（ATP）=α,β-亚甲基ATP > β,γ-亚甲基ATP >> 尿苷5'-三磷酸。苏拉明拮抗ATP（pA2 = 5.52 ± 0.17，希尔斜率 = 0.67 ± 0.08）和2-甲硫基-ATP（pA2 = 5.78 ± 0.30，希尔斜率 = 1.37 ± 0.39），而对5'-N-乙基甲酰胺腺苷（NECA）的反应不受影响。这些发现表明，苏拉明虽然相对于P1嘌呤受体对P2具有选择性，但不是真正的竞争性拮抗剂。磷酸吡哆醛-6-偶氮苯基-2',4'-二磺酸（PPADS）拮抗分离的豚鼠输精管中的ATP，但对豚鼠盲肠带中ATP的反应没有影响，表明它相对于P2Y嘌呤受体对P2X具有选择性。
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