Fisslthaler B, Schini-Kerth V B, Fleming I, Busse R
Institut für Kardiovaskuläre Physiologie, Johann Wolfgang Goethe Universität, Frankfurt am Main, Germany.
Cardiovasc Res. 1998 Apr;38(1):263-71. doi: 10.1016/s0008-6363(97)00296-4.
The factors involved in restenosis after balloon angioplasty are poorly characterized but the local concentration of the potent mitogens angiotensin II (AII) and thrombin is known to be increased at sites of vascular injury. We investigated the possibility of a synergistic interaction between AII and thrombin by studying the effects of AII on the expression of the thrombin receptor in rat aortic smooth muscle cells (VMSC).
Thrombin receptor mRNA expression was studied by Northern blot analysis and RT-PCR using total RNA extracted from VMSC or from endothelium-denuded rat aortae. As a measure of thrombin receptor protein expression, we assessed either the thrombin-stimulated release of 6-keto-prostaglandin F1 alpha from VMSC or the contraction of endothelium-denuded rat aortic rings.
The thrombin receptor mRNA was expressed at a low level in both cultured and native VMSC. AII concentration- and time-dependently increased expression of thrombin receptor mRNA in VMSC and augmented the thrombin-induced release of 6-keto-prostaglandin F1 alpha as well as the thrombin induced contraction. Blockade of the angiotensin subtype 1 (AT1) receptor by EXP3174 or D8731 prevented the AII-mediated increase in thrombin receptor expression. The effect of AII on the increase in thrombin receptor mRNA expression was enhanced by the protein kinase C inhibitor Ro 31-8220, but was unaffected by prolonged incubation with phorbol myristate acetate or the tyrosine kinase inhibitors genistein and erbstatin A.
These results demonstrate that AII enhances the expression of thrombin receptor in cultured and native VMSC. In cultured cells, this effect is mediated by the activation of the AT1 receptor subtype. This synergistic effect between AII and the thrombin receptor may promote the extensive proliferation of smooth muscle cells in response to vascular injury.
球囊血管成形术后再狭窄所涉及的因素目前尚不明确，但已知血管损伤部位强效促有丝分裂原血管紧张素 II（AII）和凝血酶的局部浓度会升高。我们通过研究 AII 对大鼠主动脉平滑肌细胞（VMSC）中凝血酶受体表达的影响，来探讨 AII 与凝血酶之间协同相互作用的可能性。
采用 Northern 印迹分析和 RT-PCR 技术，利用从 VMSC 或去内皮大鼠主动脉中提取的总 RNA，研究凝血酶受体 mRNA 的表达。作为凝血酶受体蛋白表达的衡量指标，我们评估了 VMSC 中凝血酶刺激的 6-酮-前列腺素 F1α释放情况，或去内皮大鼠主动脉环的收缩情况。
凝血酶受体 mRNA 在培养的和天然的 VMSC 中均低水平表达。AII 浓度和时间依赖性地增加 VMSC 中凝血酶受体 mRNA 的表达，并增强凝血酶诱导的 6-酮-前列腺素 F1α释放以及凝血酶诱导的收缩。EXP3174 或 D8731 对血管紧张素 1 型（AT1）受体的阻断可防止 AII 介导的凝血酶受体表达增加。蛋白激酶 C 抑制剂 Ro 31-8220 增强了 AII 对凝血酶受体 mRNA 表达增加的作用，但与佛波醇肉豆蔻酸酯乙酸酯长时间孵育或酪氨酸激酶抑制剂染料木黄酮和厄布他汀 A 对其无影响。
这些结果表明，AII 增强了培养的和天然的 VMSC 中凝血酶受体的表达。在培养细胞中，这种作用是由 AT1 受体亚型的激活介导的。AII 与凝血酶受体之间的这种协同作用可能会促进平滑肌细胞对血管损伤的广泛增殖反应。
