慢性缺氧对大鼠肺动脉舒张反应的影响

目的：探讨大鼠缺氧性肺动脉高压发生过程中肺动脉舒张反应的改变。方法：本实验比较了正常（ｎ＝１１）与慢性缺氧４天（ｎ＝１１）、间断缺氧３周（ｎ＝１１）大鼠离体肺动脉环对几种作用机制不同的血管舒张药物的反应。结果：慢性缺氧显著抑制了大鼠肺动脉环对乙酰胆碱的舒张反应（Ｐ＜０．０５），而对硝普钠（１０－７～１０－１１ｍｏｌ／Ｌ）和硝苯地平（１０－４～１０－８ｍｏｌ／Ｌ）诱发的舒张反应无明显影响；克罗卡林（１０－７～１０－１１ｍｏｌ／Ｌ）在缺氧４天大鼠肺动脉环的舒张作用显著增强（Ｐ＜０．０５）。结论：慢性缺氧显著抑制大鼠肺动脉内皮依赖性舒张反应，而对非内皮依赖性及钙通道依赖性舒张反应无明显影响；钾通道依赖性舒张反应在缺氧早期是增强的

Effect of Chronic Hypoxia on Pulmonary Vasodilation in Rats

Objective: To assess the changes of pulmonary vascular response in the development of hypoxic pulmonary hypertension in rats. Methods: The responses to various drugs of pulmonary artery rings (PAR) isolated from normal ( n =11), chronic hypoxic [hypoxia for 4 days (H4d, n =11) and intermittent hypoxia for 3 weeks (H3w, n =11)] rats were observed. Results: Comparing with normals, chronic hypoxia (H4d and H3w) could significantly inhibit the dilation of Ach (10 -4 -10 -8 mol/L, p <0 05),but had no significant influence on the dilation of SNP (10 -7 -10 -11 mol/L, p >0 05) and nifedipine (10 -4 -10 -8 mol/L, p >0 05) ; while the effect of cromakalim (10 -7 -10 -11 mol/L) increased the dilation significantly ( p <0 05) of PARs from rats in hypoxia for 4 days. Conclusion: Chronic hypoxia significantly inhibits the endothelium dependent dilation of rat PA with little influence on the endothelium independent and Ca channel dependent dilation, while K channel dependent dilation increases significantly in the early stage of hypoxia.