ERK1/2通路参与15-羟二十碳四烯酸收缩缺氧大鼠肺动脉的过程

缺氧诱导的15-羟二十碳四烯酸（15-hydroxyeicosatetraenoic acid,15-HETE）是引起肺动脉收缩的重要介导因子。15-HETE引起肺动脉收缩的信号转导途径尚不清楚。本研究旨在确定细胞外信号调节激酶1／2（extracellular signal-regulated kinase-1／2,ERK1／2）信号转导通路是否参与15-HETE收缩缺氧火鼠肺动脉的过程。采用组织浴槽肺动脉环张力检测、蛋白质免疫印迹Western blot）和免疫细胞化学方法。制备缺氧大鼠动物模型,成年雄性Wistar大鼠在低氧环境下（吸入氧分数为0．12）正常喂养9d。显微分离直径1-1．5mm肺动脉,剪成长为3mm的动脉环,进行血管张力检测。用ERK1／2上游激酶（MEK）抑制剂PD98059抑制ERK1／2活性。结果显示,PD98059可明显抑制15-HETE对缺氧大鼠肺动脉环的收缩作用。在去除内皮的肺动脉环,PD98059仍叮明显降低15-HETE的缩血管作用。Western blot和免疫细胞化学结果都显示,15-HETE能促进ERK1／2磷酸化。由此表明ERK1／2信号转导通路参与15-HETE收缩缺氧大鼠肺动脉的过程。

ERK1/2 signaling pathway is involved in 15-hydroxyeicosatetraenoic acid-induced hypoxic pulmonary vasoconstriction

Hypoxia-induced 15-hydroxyeicosatetraenoic acid (15-HETE) is an essential mediator to constrict pulmonary arteries (PA). The signaling pathway involved in 15-HETE-induced PA vasoconstriction remains obscure. The aim of the present study was to test the hypothesis that hypoxic PA constriction induced by 15-HETE was possibly regulated by the extracellular signal-regulated kinase1/2 (ERK1/2) pathway. PA ring tension measurement, Western blot and immunocytochemistry were used in the study to determine the possible role of ERK1/2 in 15-HETE-induced PA vasoconstriction. The organ bath for PA rings tension study was employed. Adult male Wistar rats were raised in hypoxic environment with fractional inspired oxygen (FIO2, 0.12) for 9 d. PA 1-1.5 mm in diameter were dissected and cut into 3 mm long rings for tension study. ERK1/2 up-stream kinase (MEK) inhibitor PD98059, which blocks the activation of ERK1/2, was used. The results showed that pretreatment of PD98059 significantly blunted 15-HETE-induced PA vasoconstrictions in the rings from hypoxic rat. Moreover, in endothelium-denuded rings, PD98059 also significantly attenuated 15-HETE-induced vasoconstriction. Phosphorylation of ERK1/2 in pulmonary arterial smooth muscle cells (PASMCs) of rat was enhanced evidently when stimulated by 15-HETE. Thus, the data suggest that ERK1/2 signaling pathway is involved in 15-HETE-induced hypoxic pulmonary vasoconstriction.