血管加压素1a与血管加压素2受体在精氨加压素调节缺氧血管平滑肌细胞蛋白激酶C表达中的作用

目的观察血管加压素1a(V1a)受体与V2受体拮抗剂对精氨加压素(AVP)调节缺氧血管平滑肌细胞(VSMC)蛋白激酶C(PKC)α,δ和ε亚型表达的影响,以及磷脂酶C(PLC)、磷脂酶D(PLD)和磷脂酶A2(PLA2)活性的变化。方法缺氧培养大鼠肠系膜上动脉VSMC,采用Western蛋白印迹法检测PKCα,δ和ε亚型蛋白表达;采用酶偶联荧光分析法测定PLC和PLD的活性,酸碱滴定法检测PLA2的活性。结果缺氧处理1.5h,VSMC胞膜PKC-α和ε亚型蛋白表达量明显升高,AVP进一步升高胞膜PKC-α和ε的表达。V1a受体拮抗剂d(CH2)5[Tyr2(Me)]AVP预处理可明显拮抗AVP诱导的胞膜PKCα和ε亚型蛋白表达升高,同时也明显拮抗AVP诱导的缺氧VSMC中PLC和PLD活性升高。而V2受体拮抗剂d(CH2)[d-Ile2Abu4]AVP对缺氧诱导的胞膜PKC-α和ε表达增加和VSMC中PLC和PLD活性升高无明显作用。结论AVP诱导PKC激活的机制可能与V1a受体介导的PLC/PLD途径有关,而V2受体在这一信号传导途径中可能并不起主要作用。

Vasopressin-1a and vasopressin-2 receptors in argipressin regulating expression of protein kinase C of vascular smooth muscle cell after hypoxia

AIM To investigate the effects of vasopressin-1a(V_1a) receptor and V₂ receptor antagonists on argipressin (AVP) regulating the expression of protein kinase C (PKC)-α, δ and ε isoforms of vascular smooth muscle cell (VSMC) and the changes in phospholipases C (PLC), D (PLD) and A₂ (PLA₂) activity. METHODS VSMCs from superior mesenteric artery of rats were hypoxia-treated for 1.5 h. The expression of PKC-α, δ and ε isoforms was detected with Western blot. The PLC and PLD activities were assayed by enzyme-coupled fluorimetric analysis, and PLA₂ activity was assayed by acid-base titration. RESULTS After hypoxia, the expression of VSMC particulate PKC-α and ε increased, and AVP treatment further increased expression of PKC-α and ε in the particulate fractions. V_1aReceptor inhibitor d(CH₂)₅［Tyr²(Me)］AVP significantly antagonized this effect of AVP, simultaneously, also antagonized AVP-induced increase in PLC and PLD activities of VSMC after hypoxia. But V₂ receptor antagonist d(CH₂)［d-Ile²Abu⁴］AVP had no significant influence on AVP-induced increase in expression of PKC-α and ε isoforms and the activities of PLC and PLD. CONCLUSION AVP induces translocation/activation of PKC isoforms in VSMC mainly through a V_1a receptor-dependent PLC/PLD mechanism, while V₂ receptor plays a lesser role in the signal transduction pathway.