模拟高原和返回平原后大鼠心肌血流量的变化

Changes of myocardial blood flow at simulated high altitude and after the return to sea level in rats

目的：观察缺氧及停止缺氧后对大鼠心肌血流量的影响。方法：３４只Ｗｉｓｔａｒ大鼠，随机分为４组：①平原对照组；②急性缺氧组；③慢性缺氧组；④返回平原组。以放射性生物微球法测定心肌血流量。结果：急性缺氧引起ＰａＯ２、心输出量及氧运送量降低，但左、右心室心肌血流量明显增加；慢性缺氧时右心室收缩压、血球压积、血液粘滞性及右心室重量指数明显增加，而心肌血流量接近正常。停止缺氧３０ｄ后，上述所有指标均与平原对照组无显著差别。结论：急性缺氧引起心肌血流量增加；慢性缺氧心肌血流量恢复正常，这可能是红细胞增多及血管中层增厚的结果。高原缺氧引起心血管变化是可逆性改变。

Objective: To observe the effects of hypoxia and normoxia on myocardial blood flow. Methods: Thirtyfour Wistar rats were randomized into four groups: ①The control group; ②Acutehypoxic group; ③Chronic hypoxic group and; ④Returntosealevel group. Myocardial blood flow was measured with radiobiological frog erythrocyte assay. Results: Acute hypoxia resulted in a decrease in PaO2, oxygen delivery and cardiac output and an increase in myocardial blood flow of the two ventricles. During chronic hypoxia, the right ventricular systolic pressure, right ventricular weight index, hemoatocrit and blood viscosity were significantly increased whereas the myocardial blood flow of the two ventricles was normal. On the 30th day after the chronic hypoxia stopped, all these parameters returned to normal levels. Conclusion: Acute hypoxia causes an increase in myocardial blood flow. It may result from the increase in blood viscosity, arterial wall thickness and collagen in arterial adventitia. The changes of cardiac function and structure induced by chronic hypoxia were reversible.