Effects of chronic alveolar hypoxia on pulmonary circulation

1)慢性缺氧条件下心脏形态特征采用新生、3周龄和8周龄Wistar雄性大鼠三组，检测其年龄依赖性变异的适应能力。将大鼠饲养至海拔2400米，饲养7 ~ 9周。在适应良好的大鼠慢性轻度缺氧时，应限制心肌肥厚，适度提高红细胞压积。右心室壁不应过度反应。线粒体很小，但晶体密度和百分比面积，估计从电子显微镜，被发现是高的。为了确定年轻自发性高血压大鼠（SHR）心脏是否对长期高海拔暴露有心肌生长的反应，将SHR饲养到海拔2400m的高海拔研究站，在那里饲养80天。慢性高海拔暴露导致两组和对照组左、右心室重量均增加。(2)高原适应性动物鼠兔的生理特征研究发现，青藏高原鼠兔具有完全适应高原的特征，特别是右室小程度肥厚、肺动脉压较低、红细胞压积较低。这些特征可能会遗传给下一代。3)缺氧肺血管收缩机制研究血管紧张素转换酶抑制剂（captoril）、钙通道阻滞剂（硝苯地平）和血栓素合成酶抑制剂对缺氧肺血管收缩的影响。卡托利和尼西平都是有效的血管舒张药物，缺氧血管张力不受环加氧酶产物的调节。

1) Cardiac morphological features under chronic hypoxia Three groups of male Wistar strain rats of newborn, 3 weeksage and 8 weeks-age were used to test the adaptative ability of age-dependent variability. Rats were raised to 2,400m altitude and had been kept for 7 to 9 weeks. In well-adapted rats under chronic mild hypoxia, cardiac hypertrophy should be restricted and haematocrit moderately elevated. Right ventricular wall should not react excessively. Mitochondria were small but cristal density and percentage area, estimated from electron micrographs, were found to be high. And to determine whether the heart of young, spontaneously hypertensive rat(SHR) could respond to chronically high altitude exposure with myocardial growth, SHR were raise to a high altitude research station at altitude of 2400m, where they were kept for 80 days. Chronic high altitude exposure caused increase of both right and left ventricular weights in both and controls.2) Physiological characteristics of Pika, as high altitude adapted animalsWe found pika, ochontona,living at Qinghai-Tibetan plateau are having completely adapted signs, especially like small degree of right ventricular hypertrophy, lower pulmonary artery pressure, and low haematocrit values. And these characteristics may have been genetically transmitted to following generation.3) Mechanism of hypoxic pulmonary vasoconstrictionWe investigated the effects of angiotensin converting enzyme inhibitor (captoril), calcium channel blocker (nifedipin), and thromboxane synthetase inhibitor on hypoxic pulmonary vasoconstriction in conscious sheep. Both captoril and nifesipin are potent vasodilating drug, and hypoxic vascular tone is not modulated by cyclooxygenase products.