内源性一氧化碳对低氧大鼠肺动脉转化生长因子-β3和Ⅰ型胶原表达的影响

目的:探讨内源性一氧化碳(CO)对低氧大鼠肺动脉胶原代谢的作用及其机制。方法:采用常压低氧大鼠肺动脉高压模型,观察血红素氧合酶(HO)抑制剂锌原卟啉-Ⅸ(ZnPP-Ⅸ)对肺动脉平均压(PAMP)和肺组织匀浆碳氧血红蛋白(HbCO)含量的影响,并用免疫组织化学和核酸原位杂交法分别观察ZnPP-Ⅸ对肺动脉转化生长因子-β₃(TGF-β₃)、Ⅰ型胶原蛋白的表达和肺动脉TGF-β₃mRNA、Ⅰ型前胶原mRNA和金属蛋白酶组织抑制因子(TIMP-1)mRNA表达的影响。结果:ZnPP-Ⅸ使低氧大鼠PAMP明显升高,肺组织匀浆CO含量明显降低;ZnPP-Ⅸ能促进TGF-β₃蛋白表达和TGF-β₃mRNA表达,显著促进低氧大鼠肺动脉Ⅰ型胶原蛋白表达和Ⅰ型前胶原mRNA表达,上调TIMP-1mRNA的表达。结论:内源性CO可能通过抑制TGF-β₃mRNA和TGF-β₃蛋白表达而抑制胶原蛋白的合成,促进胶原的降解,从而对低氧大鼠肺动脉胶原代谢发挥重要的调节作用。

Effects of endogenous carbon monoxide on the expression of transforming growth factor-beta 3 and type Ⅰcollagen of pulmonary artery in rats under hypoxia

AIM: To explore the impact of endogenous carbon monoxide (CO) on the expression of transforming growth factor-beta 3 (TGF-β₃) and type Ⅰcollagen in pulmonary artery of rats under hypoxia. METHODS: In the model of rats under hypoxic pulmonary hypertension, the measurement of pulmonary artery mean pressure (PAMP) and carboxyhemoglobin (HbCO) formation within pulmonary tissue homogenates was performed. TGF-β₃ and collagen Ⅰexpressions were detected by immunohistochemical assay. The expressions of TGF-β₃, type Ⅰ procollagen mRNA, and tissue inhibitor of metalloproteinase -1 (TIMP-1) mRNA were detected by in situ hybridization. RESULTS: ZnPP significantly increased PAMP and markedly decreased HbCO formation within lung tissue homogenates in rats under hypoxia( P< 0.01). Meanwhile, ZnPP promoted the expression of TGF-β₃ and collagen Ⅰprotein in pulmonary arteries in rats under hypoxia ( P< 0.01). ZnPP obviously elevated the expressions of TGF-β₃ mRNA, type Ⅰ procollagen mRNA, and TIMP-1 mRNA in pulmonary arteries in rats under hypoxia ( P< 0.01). CONCLUSION: Endogenous CO plays an important role in decreasing collagen synthesis and promoting degradation in pulmonary artery of rats under hypoxia by inhibiting the expression of TGF-β₃.