Centre de Recherche en Rhumatologie et Immunologie, Université Laval, Québec, QC, Canada G1V 4G2.
Cardiovasc Res. 2010 Jan 1;85(1):204-13. doi: 10.1093/cvr/cvp265.
Extracellular nucleotides are vasoactive molecules. The concentrations of these molecules are regulated by ectonucleotidases. In this study, we investigated the role of the blood vessel ectonucleotidase NTPDase1, in the vasoconstrictor effect of nucleotides using Entpd1(-/-) mice.
Immunofluorescence, enzyme histochemistry, and HPLC analysis were used to evaluate both NTPDase expression and activity in arteries and isolated vascular smooth muscle cells (VSMCs). Vascular reactivity was evaluated in vitro and mean arterial blood pressure was recorded in anesthetized mice after nucleotide i.v. infusion. Expression of nucleotide receptors in VSMCs was determined by RT-PCR. Entpd1(-/-) mice displayed a dramatic deficit of nucleotidase activity in blood vessel wall in situ and in VSMCs in comparison to control mice. In aortic rings from Entpd1(-/-) mice, UDP and UTP induced a potent and long-lasting constriction contrasting with the weak response obtained in wild-type rings. This constriction occurred through activation of P2Y(6) receptor and was independent of other uracil nucleotide-responding receptors (P2Y(2) and P2Y(4)). UDP infusion in vivo increased blood pressure and this effect was potentiated in Entpd1(-/-) mice. In addition, pressurized mesenteric arteries from Entpd1(-/-) mice displayed an enhanced myogenic response, consistent with higher local concentrations of endogenously released nucleotides. This effect was inhibited by the P2 receptor antagonist RB-2.
NTPDase1 is the major enzyme regulating nucleotide metabolism at the surface of VSMCs and thus contributes to the local regulation of vascular tone by nucleotides.
细胞外核苷酸是血管活性分子。这些分子的浓度受核苷酸酶的调节。在这项研究中，我们使用 Entpd1(-/-) 小鼠研究了血管外核苷酸酶 NTPDase1 在核苷酸的血管收缩作用中的作用。
免疫荧光、酶组织化学和 HPLC 分析用于评估动脉和分离的血管平滑肌细胞 (VSMC) 中的 NTPDase 表达和活性。在体外评估血管反应性，并在静脉输注核苷酸后在麻醉小鼠中记录平均动脉血压。通过 RT-PCR 确定 VSMC 中核苷酸受体的表达。与对照小鼠相比，Entpd1(-/-) 小鼠在血管壁原位和 VSMC 中表现出核苷酸酶活性的明显缺陷。在 Entpd1(-/-) 小鼠的主动脉环中，UDP 和 UTP 诱导出强烈而持久的收缩，与野生型环中获得的弱反应形成对比。这种收缩是通过激活 P2Y(6)受体发生的，与其他尿嘧啶核苷酸反应受体 (P2Y(2) 和 P2Y(4)) 无关。UDP 在体内输注会升高血压，这种效应在 Entpd1(-/-) 小鼠中增强。此外，Entpd1(-/-) 小鼠的加压肠系膜动脉显示出增强的肌源性反应，与内源性释放的核苷酸的局部浓度升高一致。这种效应被 P2 受体拮抗剂 RB-2 抑制。
NTPDase1 是调节 VSMC 表面核苷酸代谢的主要酶，因此有助于核苷酸对血管张力的局部调节。
