Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, John Arbuthnott Building, 27 Taylor Street, Glasgow G4 ONR, United Kingdom.
Eur J Pharmacol. 2010 Dec 15;649(1-3):342-8. doi: 10.1016/j.ejphar.2010.09.041. Epub 2010 Sep 22.
Previous studies indicated that a P2X receptor other than the P2X1 subtype might be present in rat large, but not small pulmonary arteries. The aim here was to characterise further these P2X receptors. Isometric tension was recorded from rat isolated small (i.d. 250-500 μm) and large pulmonary artery (i.d. 1-1.5 mm) rings mounted on a wire myograph. In both tissues the P2X receptor agonist α,β-meATP evoked rapidly-developing contractions that were inhibited by the P2X antagonists NF449, PPADS and suramin in a concentration-dependent manner and eventually abolished by each. The rank order of the potency in both tissues was NF449>PPADS=suramin. For each antagonist there was no significant difference between its potency in the small and large pulmonary arteries. Prolonged administration of a high concentration of α,β-meATP induced complete desensitisation in both tissues. RT-PCR followed by PCR with specific oligonucleotide primers, identified mRNA for all seven P2X subunits. Subtype-specific antibodies showed strong, punctate P2X1 receptor-like immunoreactivity in the majority of cells and faint, punctate staining with the anti-P2X2 and anti-P2X4 antibodies, whilst P2X5-like immunoreactivity was barely detectable and no P2X3, P2X6, and P2X7 receptor-like immunoreactivity was seen. No differences in P2X mRNA and protein expression were seen between small and large pulmonary arteries. In conclusion, the pharmacological properties and mRNA and protein expression profiles of P2X receptors in rat small and large pulmonary arteries are very similar. Thus P2X1 appears to be the predominant P2X subunit functionally expressed in smooth muscle cells of rat small and large pulmonary arteries.
先前的研究表明，大鼠的大动脉中可能存在一种不同于 P2X1 亚型的 P2X 受体，但在小动脉中不存在。本研究旨在进一步对这些 P2X 受体进行描述。通过将大鼠小（内径 250-500μm）和大动脉（内径 1-1.5mm）的血管环安装在钢丝肌描记器上，从大鼠分离的小（内径 250-500μm）和大动脉（内径 1-1.5mm）环中记录等长张力。在这两种组织中，P2X 受体激动剂 α,β-meATP 引起迅速发展的收缩，该收缩可被 P2X 拮抗剂 NF449、PPADS 和苏拉明浓度依赖性抑制，并最终被每种拮抗剂完全抑制。在这两种组织中，NF449>PPADS=苏拉明的效力顺序。对于每种拮抗剂，其在小和大动脉中的效力之间没有显着差异。长时间给予高浓度的 α,β-meATP 会导致两种组织完全脱敏。通过 RT-PCR 随后使用特异性寡核苷酸引物进行 PCR，鉴定出所有七种 P2X 亚基的 mRNA。亚基特异性抗体在大多数细胞中显示出强烈的、点状的 P2X1 受体样免疫反应性，而抗 P2X2 和抗 P2X4 抗体则显示出微弱的、点状的染色，而 P2X5 样免疫反应性几乎检测不到，并且没有 P2X3、P2X6 和 P2X7 受体样免疫反应性。小和大动脉之间的 P2X mRNA 和蛋白表达没有差异。总之，大鼠小和大动脉中 P2X 受体的药理学特性以及 mRNA 和蛋白表达谱非常相似。因此，P2X1 似乎是大鼠小和大动脉平滑肌细胞中功能性表达的主要 P2X 亚基。
