Stoll M, Steckelings U M, Paul M, Bottari S P, Metzger R, Unger T
Department of Pharmacology, University of Kiel, Germany.
J Clin Invest. 1995 Feb;95(2):651-7. doi: 10.1172/JCI117710.
Angiotensin II (ANG II) is known to be a potent growth promoting factor for vascular smooth muscle cells and fibroblasts but little is known about its influence on growth in endothelial cells. We studied the effects of ANG II on endothelial growth and the role of the angiotensin receptor subtypes involved. Proliferation of rat coronary endothelial cells (CEC) and rat vascular smooth muscle cells (VSMC) was determined by [3H]thymidine incorporation, the MTT-test and by directly counting cells in a coulter counter. Angiotensin AT1- and AT2-receptors were demonstrated by binding studies and by the presence of their respective mRNA through reverse transcription polymerase chain reaction (RT-PCR). In contrast to VSMC, which in culture only express the AT1-receptor, CEC express both, AT1- and AT2-receptors simultaneously up to the third passage. Whereas ANG II stimulated growth of quiescent VSMC, an effect abolished by pretreatment with the AT1-receptor antagonist, losartan, ANG II did not induce proliferation in quiescent CEC. However, after pretreatment of quiescent endothelial cells (< passage 4) with the AT2-receptor antagonist, PD 123177, ANG II induced proliferation. This effect was reversed by additional pretreatment with losartan. ANG II significantly inhibited the proliferation of bFGF-stimulated CEC in a dose-dependent manner by maximally 50%. This effect was prevented by PD 123177 while losartan was ineffective. The AT2-receptor agonist, CGP 42112, mimicked the antiproliferative actions of ANG II, confirming the specificity of the effect. Our results show that the growth modulating actions of ANG II depend on the type of angiotensin receptor present on a given cell. In coronary endothelial cells, the antiproliferative actions of the AT2-receptor offset the growth promoting effects mediated by the AT1-receptor.
已知血管紧张素II（ANG II）是血管平滑肌细胞和成纤维细胞的一种强大的生长促进因子，但关于其对内皮细胞生长的影响却知之甚少。我们研究了ANG II对内皮生长的影响以及所涉及的血管紧张素受体亚型的作用。通过[3H]胸苷掺入、MTT试验以及在库尔特计数器中直接计数细胞来测定大鼠冠状动脉内皮细胞（CEC）和大鼠血管平滑肌细胞（VSMC）的增殖。通过结合研究以及通过逆转录聚合酶链反应（RT-PCR）检测其各自mRNA的存在来证实血管紧张素AT1和AT2受体。与仅在培养中表达AT1受体的VSMC不同，CEC在传代至第三代时同时表达AT1和AT2受体。虽然ANG II刺激静止VSMC的生长，这种作用可被AT1受体拮抗剂氯沙坦预处理所消除，但ANG II并未诱导静止CEC的增殖。然而，在用AT2受体拮抗剂PD 123177预处理静止内皮细胞（<第4代）后，ANG II诱导了增殖。用氯沙坦进一步预处理可逆转这种作用。ANG II以剂量依赖性方式显著抑制bFGF刺激的CEC的增殖，最大抑制率为50%。PD 123177可阻止这种作用，而氯沙坦则无效。AT2受体激动剂CGP 42112模拟了ANG II的抗增殖作用，证实了该作用的特异性。我们的结果表明，ANG II的生长调节作用取决于给定细胞上存在的血管紧张素受体类型。在冠状动脉内皮细胞中，AT2受体的抗增殖作用抵消了由AT1受体介导的生长促进作用。
