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目的:探讨亚硝酸钠对高肺血流肺动脉高压大鼠的影响及亚硝酸盐转化为NO的可能机制,为临床治疗先天性心脏病(congenital heart disease,CHD)肺动脉高压提供依据。方法:健康清洁级雄性SD大鼠50只,体质量200~230 g,按照随机数字表法随机分为5组:假手术组(S组)、肺动脉高压组(P组)、亚硝酸钠组(N组)、亚硝酸钠+黄嘌呤氧化还原酶(xanthine oxidase,XOR)抑制剂组(NX组)、XOR抑制剂组(X组),每组10只。S组仅开腹暴露腹主动脉和下腔静脉,其余各组进行腹主动脉-下腔静脉造瘘手术,建立左向右分流高肺血流肺动脉高压大鼠模型。术后11周分别给予N组和NX组亚硝酸钠6 mg/kg,X组XOR抑制剂别嘌呤醇30 mg/kg灌胃干预,NX组在亚硝酸钠给药前1 h给予XOR抑制剂别嘌呤醇30 mg/kg,其余2组给予等容量的生理盐水,每天1次,共3周。14周时监测平均肺动脉压(mean pulmonary artery pressure,m PAP)和平均动脉压(mean arterial pressure,MAP);计算右心室肥厚指数(RVHI)=右心室质量/(左心室质量+室间隔质量)[RV/(LV+IS)];硝酸还原酶法检测血及肺组织中NO含量;HE染色光镜下观察肺动脉的病理学结果;Western blot检测肺组织内皮型一氧化氮合酶(endothelial nitric oxide synthase,e NOS)、XOR蛋白含量变化。结果:与S组比较,P组大鼠m PAP、RV/(LV+IS)显著升高(P=0.000),血清NO含量降低(P=0.000),肺匀浆NO含量差异无统计学意义(P>0.05),光镜下肺动脉管壁增厚,e NOS蛋白含量表达降低(P=0.005);与P组比较,N组、NX组和X组大鼠m PAP和RV/(LV+IS)明显降低(P<0.05)、血清NO含量升高(P=0.000),N组肺匀浆NO含量差异无统计学意义(P>0.05),NX组和X组肺匀浆NO含量降低(P=0.000),N组e NOS和XOR蛋白含量表达增加(P=0.000);与N组比较,NX组和X组m PAP、RV/(LV+IS)差异无统计学意义(P>0.05),NX组和X组血清和肺匀浆NO含量降低(P=0.000)、XOR表达降低(P=0.000)。N组、NX组、X组光镜下肺动脉病理学损伤程度明显减轻。5组大鼠MAP比较差异无统计学意义(P>0.05)。结论:亚硝酸钠(6 mg/kg)灌胃能降低高肺血流肺动脉高压大鼠平均肺动脉压力,减轻肺血管重塑;亚硝酸钠降低肺动脉的压力不完全被XOR抑制剂阻断;同时实验中发现XOR抑制剂本身具有降低肺动脉压力的作用。亚硝酸钠转化为NO的机制需要进一步研究。
Objective: To investigate the effect of sodium nitrite on pulmonary hypertension rats with high pulmonary blood flow and the possible mechanism of nitrite conversion to NO, which may provide the basis for the clinical treatment of pulmonary hypertension in congenital heart disease (CHD). Methods: Fifty healthy and clean male Sprague-Dawley rats weighing 200-230 g were randomly divided into 5 groups according to the random number table: sham operation group (S group), pulmonary hypertension group (P group), sodium nitrite group (Group N), sodium nitrite + xanthine oxidase (XOR) inhibitor group (group NX), and group XOR inhibitor (group X) with 10 rats in each group. The abdominal aorta and inferior vena cava were exposed only to the abdominal aorta in group S, and abdominal aorta-inferior vena cava ostomy were performed in the remaining groups to establish a rat model of pulmonary hypertension with left-to-right shunt and high pulmonary blood flow. The rats in group N and group NX were given 6 mg / kg of sodium nitrite at 11 weeks after operation, and alloxan 30 mg / kg as XOR inhibitor in group X were administered intragastrically. The rats in group NX were given XOR inhibitor 1 h before sodium nitrite Allopurinol 30 mg / kg, the remaining two groups were given equal volume of saline once a day for 3 weeks. Mean pulmonary artery pressure (m PAP) and mean arterial pressure (MAP) were monitored at 14 weeks; RVHI was calculated as right ventricular mass / (left ventricular mass plus ventricular septal mass) [RV / (LV + IS)]. Nitric acid reductase method was used to detect the content of NO in blood and lung tissue. The pathological results of pulmonary artery were observed by HE staining. The expression of endothelial nitric oxide synthase oxide synthase, eNOS), XOR protein content changes. Results: Compared with group S, the levels of mPAP and RV / (LV + IS) in group P were significantly increased (P = 0.000), the content of NO in serum was lower (P = 0.000), while the content of NO in lung homogenate was no significant difference (P> 0.05). Pulmonary artery wall thickening and eNOS protein expression decreased (P = 0.005) under light microscope. Compared with P group, m PAP and RV / (LV + (P <0.05), NO content in serum (P = 0.000), NO content in lung homogenate of N group was not significantly different (P> 0.05) (P = 0.000). The expression of eNOS and XOR in N group increased (P = 0.000). Compared with N group, there was no significant difference in mPa, RV / (LV + IS) 0.05). The content of NO in serum and lung homogenate decreased in group NX and group X (P = 0.000), and decreased in XOR (P = 0.000). The pathological damage of pulmonary artery in group N, group NX and group X was significantly reduced under light microscope. There was no significant difference in MAP between the 5 groups (P> 0.05). CONCLUSION: Sodium nitrite (6 mg / kg) can reduce the average pulmonary artery pressure and reduce pulmonary vascular remodeling in rats with pulmonary hypertension with high pulmonary artery pressure. The sodium nitrite reduces the pulmonary artery pressure not completely blocked by XOR inhibitor. Meanwhile, XOR inhibitors have been found in experiments to reduce the pulmonary artery pressure. The mechanism of sodium nitrite into NO needs further study.