实验性心房颤动血栓形成时内皮型一氧化氮合酶和纤溶酶原激活剂抑制物-1的变化

目的研究心房颤动(房颤)犬心房心内膜一氧化氮(NO)浓度、内皮型一氧化氮合酶(eNOS)和纤溶酶原激活剂抑制物-1(PAl-1)蛋白表达的变化,探讨房颤左房血栓形成的可能机制。方法应用埋藏式高频心脏起搏器快速起搏心房(400次／min)6周,建立房颤犬动物模型。采用ISO-NOP3005N0敏感电极测定心内膜NO含量,Western blot和免疫组化检测eNOS、PAl-1蛋白表达,酶联免疫吸附双抗体夹心法检测血浆PAl-1含量。结果房颤组左房心内膜NO含量明显低于窦性心律组,eNOS蛋白表达下调,PAl-1蛋白表达上调,右房无明显变化。房颤组血浆PAl-1含量亦明显高于窦性心律组。结论房颤引起的左房心内膜NO含量降低、eNOS蛋白表达下调、PAl-1蛋白表达上调可能是左房血栓形成的重要原因。

The experimental study on changes of endothelial nitric oxide synthase and plasminogen activator inhibitor-1 protein in the canine atrial fibrillation model

OBJECTIVE: To evaluate the changes in the expressions of endothelial nitric oxide synthase (eNOS) and plasminogen activator inhibitor-1 (PAI-1) and the alterations of nitric oxide (NO) concentration in atrial endocardium in atrial fibrillation (AF) in order to investigate the mechanisms that contribute to thrombosis. METHODS: In canine AF was produced with rapid atrial pacing at 400 bpm for 6 weeks, whereas the controls had no atrial pacing. NO production was measured by NO-specific microelectrode. The expression of endocardial eNOS and PAI-1 protein were determined by Western blot analysis and immunohistochemical Staining. Plasma levels of PAI-1 were analysed by Enzyme-linked immunoadsorbent assay. RESULTS: Left atrial NO concentration was decreased in AF than that in controls [(23.4 +/- 5.8)nmol/L vs (63.8 +/- 16.1)nmol/L, P < 0.01]. Endocardial eNOS expression was also significantly decreased (855 +/- 217 vs 2320 +/- 694, P < 0.05), whereas the expression of the PAI-1 was increased (3164 +/- 827 vs 1371 +/- 352, P < 0.01). Neither NO concentration, nor PAI-1, eNOS expression were altered in the right atria at the same time. A significant increase for plasma levels of PAI-1 was also detected in AF group. No correlation was found between eNOS and PAI-1 protein expression (r = 0.217, P > 0.05). CONCLUSION: In the canine model AF was associated with a marked decrease in endocardial NOS expression and NO concentration and with an increase in PAI-1 expression in the left atrium, which may contribute to the thrombosis in AF.