School of Biomedical Sciences, Queen's Medical Centre, University of Nottingham, Medical School, Nottingham, UK.
Purinergic Signal. 2012 Jun;8(2):287-93. doi: 10.1007/s11302-011-9284-1. Epub 2011 Nov 24.
We have previously demonstrated that the thromboxane-mimetic U46619 enhances α(2)-adrenoceptor-mediated contractions through increased activation of extracellular signal-regulated kinase (ERK). In this study, we determined whether U46619 also enhances P2X-mediated contractions through the same pathway. Segments of porcine splenic artery were mounted in isolated tissue baths. Tissues were pre-contracted with U46619 to 10-20% of the response to 60 mM KCl prior to addition of α,β-methylene ATP (P2X receptor agonist). The effect of inhibition of ERK activation with the mitogen-activated protein (MAP)/ERK kinase inhibitor PD98059 (50 μM), Rho kinase inhibition with Y27632 (10 μM), p38 MAP kinase with SB203580 (10 μM) or L-type calcium channels with nifedipine (1 μM) on both the direct and enhanced contractions was then determined. U46619 enhanced the contractions to α,β-methylene ATP. Although PD98059 inhibited the direct contractions to α,β-methylene ATP, it had no effect on the U46619-enhanced contractions. Similarly, Y27632 and SB203580 inhibited the direct contractions to α,β-methylene ATP, but had no effect on the enhanced contractions. Nifedipine inhibited the responses to α,β-methylene ATP in the absence and presence of U46619. This study demonstrates that pre-contraction with U46619 enhances P2X-mediated contractions in the porcine splenic artery through a mechanism independent of ERK, Rho kinase and p38 MAP kinase. Further studies are required to determine the exact mechanism involved.
我们之前的研究表明，血栓烷类似物 U46619 通过增加细胞外信号调节激酶（ERK）的激活来增强 α(2)-肾上腺素受体介导的收缩。在这项研究中，我们确定 U46619 是否也通过相同的途径增强 P2X 介导的收缩。将猪脾动脉段安装在离体组织浴中。在加入 α，β-亚甲基 ATP（P2X 受体激动剂）之前，用 U46619 将组织预收缩至对 60 mM KCl 反应的 10-20%。然后，用丝裂原激活蛋白（MAP）/ERK 激酶抑制剂 PD98059（50 μM）抑制 ERK 激活、Rho 激酶抑制剂 Y27632（10 μM）、p38 MAP 激酶抑制剂 SB203580（10 μM）或 L-型钙通道抑制剂硝苯地平（1 μM）对直接和增强的收缩的影响。U46619 增强了对 α，β-亚甲基 ATP 的收缩反应。尽管 PD98059 抑制了对 α，β-亚甲基 ATP 的直接收缩，但对 U46619 增强的收缩没有影响。同样，Y27632 和 SB203580 抑制了对 α，β-亚甲基 ATP 的直接收缩，但对增强的收缩没有影响。硝苯地平抑制了 U46619 存在和不存在时对 α，β-亚甲基 ATP 的反应。本研究表明，U46619 的预收缩通过独立于 ERK、Rho 激酶和 p38 MAP 激酶的机制增强了猪脾动脉中的 P2X 介导的收缩。需要进一步的研究来确定涉及的确切机制。
