抑制NADPH氧化酶对心力衰竭兔心肌钙调节蛋白的影响

Effects of NADPH oxidase inhibition on cardiac function and myocardial calcium regulatory proteins in rabbits with heart failure

目的探讨抑制NADPH氧化酶对心力衰竭（心衰）兔心功能的影响及其机制。方法通过超容量负荷联合压力负荷建立家兔心衰模型，以NADPH氧化酶特异性抑制剂apoeynin给予干预。8周后，观察兔心脏结构和功能的变化，并检测心肌NADPH氧化酶活性以及心肌肌浆网钙泵（sarcoplasmic reticulum Ca^2＋ ATPase，SERCA2a）、雷诺定受体2（ryanodine receptor 2，RyR2）、受磷蛋白（phospholamban，PLB）和钠钙交换体（sodium—calcium exchanger，NCX）基因表达的变化。结果心衰兔出现明显的心脏扩大和心功能异常，这些改变与心肌NADPH氧化酶活性增加、SERCA2a、RyR2和PLBmRNA表达降低以及NCX mRNA表达增加相关。apocynin显著抑制心衰兔心肌NADPH氧化酶活性（P〈0．05），上凋SERCA2a、RyR2和PLB mRNA表达（SERCA2a／GAPDH比值：0．63±0．11与0．34±0．08，RyR2／GAPDH比值：0．23±0．04与0．17±0．06，PLB／GAPDH比值：1．28±0．13与0．95±0．09，P〈0．05），下调NCX mRNA表达（NCX／GAPDH比值：0．67±0．10与0．95±0．12，P〈0．05），并改善心功能[左室射血分数（60．06±10．07）％与（38．87±3．31）％，左室短轴缩短率（30．12±6．56）％与（17．40±2．45）％，P〈0．05]。结论抑制NADPH氧化酶能够调节心衰时心肌钙调节蛋白异常表达，这可能是其改善心衰时心功能的分子机制。

Objective To investigate the effects of NADPH oxidase inhibition on cardiac function and myocardial calcium regulatory proteins mRNA expressions in rabbits with heart failure （HF）. Methods HF was induced by experimental aortic insufficiency and abdominal aortic constriction, HF animals were treated with oral apocynin （ 15 mg/d）, a NADPH oxidase inhibitor or equal dose placebo. Eight weeks later, cardiac function was measured by echocardiography. Myocardial NADPH oxidase activity was evaluated by NADPH dependent superoxide production examined using superoxide dismutase-inhibitable cytochrome c reduction. Sarcoplasmic reticulum Ca^2 ＋ ATPase （ SERCA2a）, ryanodine receptor 2 （ RyR2）, phospholamban （PLB） and sodium-calcium exchanger （NCX） were determined by RT-PCR. Results Rabbits with HF developed ventricular dilatation and cardiac dysfunction, as well as increase in myocardial NADPH oxidase activity, decreases in mRNA expression of SERCA2a, RyR2 and PLB, and increase in mRNA expression of NCX. Apocynin significantly reduced NADPH oxidase activity （P 〈 0. 05 ）, upregulated SERCA2a, RyR2 and PLB mRNA expressions （ SERCA2a/GAPDH ： 0. 63 ± 0. 11 vs. 0. 34 ± 0. 08 , RyR2/GAPDH ： 0. 23 ±0.04 vs. 0. 17 ±0.06,PLB/GAPDH：1.28 ±0. 13 vs. 0.95 ±0.09, P 〈 0.05）, downregulated NCX mRNA expression （ NCX/GAPDH ： 0. 67 ±0. 10 vs. 0. 95 ± 0. 12, P 〈 0. 05 ）, and improved cardiac function [ LVEF ： （ 60. 06 ± 10. 07 ） % vs. （ 38. 87 ± 3.31 ） % , LVFS ： （ 30. 12 ± 6.56）% vs. （17.40 ±2.45）% ,P〈0.05] in rabbits with HF. Conclusion NADPH oxidase inhibition improves cardiac function possibly by preventing abnormal alterations in myocardial calcium regulatory proteins in failing heart.