P2核苷酸受体激动剂介导的大鼠门静脉内皮非依赖性舒张对胞外核苷酸酶活性和A2A受体的依赖性

Dependence of P2-nucleotide receptor agonist-mediated endothelium-independent relaxation on ectonucleotidase activity and A2A-receptors in rat portal vein.

作者信息

Guibert C, Loirand G, Vigne P, Savineau J P, Pacaud P

机构信息

IPMC-CNRS UPR411, Valbonne, France.

出版信息

Br J Pharmacol. 1998 Apr;123(8):1732-40. doi: 10.1038/sj.bjp.0701773.

DOI:10.1038/sj.bjp.0701773

PMID:9605582

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1565328/

Abstract

The mechanism of action of P2 nucleotide receptor agonists that produce endothelium-independent relaxation and the influence of ecto-ATPase activity on this relaxing effect have been investigated in rat portal vein smooth muscle. 2. At 25 degrees C, ATP, 2-methylthioATP (2-MeSATP) and 2-chloroATP (2-ClATP), dose-dependently inhibited spontaneous contractile activity of endothelium-denuded muscular strips from rat portal vein. The rank order of agonist potency defined from the half-inhibitory concentrations was 2-CIATP (2.7+/-0.5 microM, n=7) >ATP (12.9+/-1.1 microM, n=9) > or =2-MeSATP (21.9+/-4.8 M, n=4). In the presence of alphabeta-methylene ATP (alphabeta-MeATP, 200 microM) which itself produced a transient contractile effect, the relaxing action of ATP and 2-MeSATP was completely abolished and that of 2-ClATP strongly inhibited. 3. The non-selective P2-receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS, 100 microM) did not affect the relaxation induced by ATP, 2-MeSATP, and 2-ClATP. 4. The A2A-adenosine receptor antagonist ZM 241385 inhibited the ATP-induced relaxation in a concentration-dependent manner (1-100 nM). In the presence of 100 nM ZM 241385, the relaxing effects of 2-MeSATP and 2-ClATP were also inhibited. 5. ADP, AMP and adenosine also produced concentration-dependent inhibition of spontaneous contractions. The relaxing effects of AMP and adenosine were insensitive to alphabeta-MeATP (200 microM) but were inhibited by ZM 241385 (100 nM). 6. Simultaneous measurements of contraction and ecto-ATPase activity estimated by the degradation of [gamma-32P]-ATP showed that muscular strips rapidly (10-60 s) hydrolyzed ATP. This ecto-ATPase activity was abolished in the presence of EDTA and was inhibited by 57+/-11% (n=3) by 200 microM alphabeta-MeATP. 7. These results suggest that ATP and other P2-receptor agonists are relaxant in rat portal vein smooth muscle, because ectonucleotidase activity leads to the formation of adenosine which activates A2A-receptors.

摘要

已在大鼠门静脉平滑肌中研究了产生非内皮依赖性舒张作用的P2核苷酸受体激动剂的作用机制，以及胞外ATP酶活性对这种舒张作用的影响。2. 在25℃时，ATP、2-甲硫基ATP（2-MeSATP）和2-氯ATP（2-ClATP）剂量依赖性地抑制大鼠门静脉去内皮肌条的自发收缩活性。由半数抑制浓度确定的激动剂效力顺序为2-ClATP（2.7±0.5微摩尔，n = 7）＞ATP（12.9±1.1微摩尔，n = 9）≥2-MeSATP（21.9±4.8微摩尔，n = 4）。在存在自身产生短暂收缩作用的αβ-亚甲基ATP（αβ-MeATP，200微摩尔）时，ATP和2-MeSATP的舒张作用完全被消除，2-ClATP的舒张作用被强烈抑制。3. 非选择性P2受体拮抗剂磷酸吡哆醛-6-偶氮苯基-2'，4'-二磺酸（PPADS，100微摩尔）不影响ATP、2-MeSATP和2-ClATP诱导的舒张。4. A2A-腺苷受体拮抗剂ZM 241385以浓度依赖性方式（1 - 100纳摩尔）抑制ATP诱导的舒张。在存在100纳摩尔ZM 241385时，2-MeSATP和2-ClATP的舒张作用也被抑制。5. ADP、AMP和腺苷也产生浓度依赖性的自发收缩抑制作用。AMP和腺苷的舒张作用对αβ-MeATP（200微摩尔）不敏感，但被ZM 241385（100纳摩尔）抑制。6. 通过[γ-32P]-ATP降解估计的收缩和胞外ATP酶活性的同步测量表明，肌条迅速（10 - 60秒）水解ATP。这种胞外ATP酶活性在存在EDTA时被消除，被200微摩尔αβ-MeATP抑制57±11%（n = 3）。7. 这些结果表明，ATP和其他P2受体激动剂在大鼠门静脉平滑肌中具有舒张作用，因为胞外核苷酸酶活性导致腺苷形成，腺苷激活A2A受体。