中文摘要：

目的：为了全面地反映急进高原过程中机体的一些真实改变，本实验通过动态监测清醒和麻醉2种不同状态下大鼠血流动力学指标，旨在探讨清醒和麻醉状态大鼠在急性缺氧时血流动力学的差异，并以此进一步探讨其可能的机制。方法：实验将SD大鼠随机分为麻醉组、清醒组、5000 m麻醉对照（ A-5000-control）组、5000 m麻醉氨基胍（ A-5000-AG）组、5000 m清醒对照（ C-5000-control）组和5000 m清醒氨基胍（ C-5000-AG）组。麻醉组和清醒组大鼠在低压氧舱从2260 m开始，以2 m／s模拟急进高原5000 m过程；其余4组均在模拟5000 m海拔条件下进行。实验期间通过PowerLab生理记录仪实时、动态地监测整个过程中大鼠的系统动脉压（ system arterial pressure， Psa）、中心静脉压（ central venous pressure， CVP）、心率（ heart rate， HR）和呼吸频率（ breathing rate， BR）。结果：清醒组大鼠的HR和BR明显高于麻醉组，但MAP明显低于麻醉组。随着海拔的逐渐升高，清醒组和麻醉组大鼠均出现平均动脉压（ mean arterial pressure，MAP）降低，且清醒组大鼠降低更为显著。另外，在5000 m时，清醒组大鼠HR明显降低，而整个过程中2组大鼠的BR均无明显改变。静脉注射诱导型一氧化氮合酶（ inducible nitric oxide synthase，iNOS）抑制剂氨基胍后，C-5000-AG组和A-5000-AG组大鼠动脉血压均明显升高，而HR和BR未见明显变化。结论：在急进高原过程中，血压和心率会明显下降，而呼吸频率变化不大。该现象可能的机制为：急性缺氧早期机体启动自我保护机制，活化iNOS，大量产生并释放NO，使血管舒张，可调节肺通气、引起血压下降；达到海拔5000 m左右甚至更早时，机体可能出现失代偿，使心率减慢，引起血压进一步降低。由于受麻醉药物戊巴比妥钠的影响，麻醉状态的大鼠血压下降出现得较为迟缓，而清醒大

英文摘要：

AIM：This study continuously monitors the hemodynamic changes in conscious and anesthetic rats during rapid ascent to high altitude to investigate whether there is difference between the 2 conditions and discuss the rela-ted underlying mechanism.METHODS： Sprague-Dawley rats were randomly divided into conscious group, anesthetic group, anesthetic-5000-control （ A-5000-control） group, anesthetic-5000-aminoguanidine （ A-5000-AG） group, conscious-5000-control （ C-5000-control ） group and conscious-5000-aminoguanidine （ C-5000-AG ） group.The rats in anesthetic group and conscious group were kept in a hypobaric chamber, in which the simulated altitude was increased from 2 260 m to 5 000 m at 2 m/s, and the rats in other 4 groups were at 5 000 m.The system arterial pressure （ Psa） , central venous pressure （ CVP） , heart rate （ HR） and breathing rate （ BR） were directly and continuously displayed and digitally recorded by a high-performance data acquisition （PowerLab 16/35, AD Instruments） at 200 Hz.RESULTS： The HR and BR in the conscious rats were higher and MAP was lower than those in the anesthetic rats obviously.A significant decrease in＆nbsp;mean arterial pressure （ MAP） in conscious and anesthetic groups was observed following the increase in the altitude levels, and the net decrease in MAP in conscious group was significantly greater.Additionally, HR in the conscious rats was sig-nificantly lower at 5 000 m than that of the initial level.The rats in C-5000-AG group and A-5000-AG group showed a sig-nificant increase in the arterial pressure after the intravenous injection of AG, a selective inhibitor of inducible nitric oxide synthase （ iNOS） , and no marked change of HR and BR was found.CONCLUSION： Blood pressure and HR decrease during rapid ascent to high altitude, while the change of BR is not obvious.The mechanisms of self-safety would be trig-gered in the early stage of hypoxia, which activates iNOS and then leads to a larger number of nitric oxide.Plentifu