Objective: To study the effect of calcium-sensitive receptors (CaSR) on the expression of endothelial nitric oxide synthase (eNOS) and the concentration of nitric oxide (NO) in a neonatal mouse model of persistent pulmonary hypertension (PPH).
Methods: Eighty neonatal C57BL/6 mice were randomly divided into control, PPH, agonist and antagonist groups. The control group was exposed to air, and the other three groups were exposed to 12% oxygen. The agonist and antagonist groups were intraperitoneally injected with a CaSR agonist (GdCl3 16 mg/kg) and a CaSR antagonist (NPS2390, 1 mg/kg), respectively, while the PPH and control groups were intraperitoneally injected with normal saline instead. All mice were treated for 14 days. Alveolar development and pulmonary vessels were assessed by hematoxylin-eosin staining. The protein and mRNA expression of eNOS and its localization in lung tissues were determined by Western blot, qRT-PCR and immunohistochemistry. The levels of brain natriuretic peptide (BNP) and NO in lung homogenate were determined using ELISA.
Results: Compared with the control group, the PPH and agonist groups showed significant increases in alveolar mean linear intercept, the percent wall thickness of pulmonary arterioles, right to left ventricular wall thickness ratio (RV/LV) and BNP concentration, but a significant reduction in radial alveolar count (P<0.05). The antagonist group had significant improvements in all the above indices except RV/LV compared with the PPH and agonist groups (P<0.05). Compared with those in the control group, the protein and mRNA expression of eNOS and NO concentration were significantly increased in the PPH group and increased more significantly in the agonist group, but were significantly reduced in the antagonist group (P<0.05).
Conclusions: CaSR plays an important role in the development of PPH in neonatal mice, possibly by increasing eNOS expression and NO concentration.
目的: 探讨钙敏感受体（CaSR）在持续性肺动脉高压（PPH）新生小鼠模型中对内皮型一氧化氮合酶（eNOS）表达及一氧化氮（NO）浓度的影响。
方法: 将80只新生C57BL/6小鼠随机分为对照组、PPH组、激动剂组和抑制剂组。对照组小鼠暴露于空气中，PPH组、激动剂组和抑制剂组小鼠暴露于12%的氧浓度中。激动剂组和抑制剂组分别腹腔注射CaSR激动剂（GdCl3）16 mg/kg、CaSR抑制剂（NPS2390）1 mg/kg，PPH组和对照组以生理盐水替代，共14 d。采用苏木精-伊红染色检测各组小鼠肺泡和肺血管变化；采用Westernblot、qRT-PCR和免疫组化检测各组小鼠肺组织中eNOS蛋白、mRNA的表达；采用ELISA法分别检测肺组织匀浆中脑利钠肽（BNP）及NO的含量。
结果: 与对照组相比，PPH组和激动剂组肺泡平均内衬间隔、肺小动脉血管壁厚度、右心室与左心室壁厚度比（RV/LV）及BNP浓度均明显增大，径向肺泡计数明显减少（P < 0.05）；除RV/LV外，上述指标在抑制剂组均较PPH组和激动剂组有所改善（P < 0.05）。与对照组相比，eNOS蛋白、mRNA表达量及NO浓度在PPH组明显增高，在激动剂组中表达水平进一步增加，而在抑制剂组中表达减少（P < 0.05）。
结论: CaSR可能通过影响eNOS的表达和NO浓度在新生小鼠PPH发病中发挥重要作用。