急性低氧对高原土生动物藏系绵羊血气的影响

为了探讨急性低氧时藏系绵羊(Ovis aries)的血气特点,揭示其低氧适应机制,将7只雄性藏系绵羊和5只雄性移居绵羊分别置于高低压氧舱内,测定模拟海拔0、2 300和4 500 m时各动物清醒状态下的血气指标。用热稀释法测定心输出量。使用血气分析仪和EG7血样板,测定动脉及混合静脉血的血气指标,按Ficks方法计算氧耗量。结果显示,随着模拟海拔高度的升高,藏羊和移居羊的动静脉血氧饱和度(So2)、氧分压(Po2)、二氧化碳分压(Pco2)都呈明显下降趋势(P<0.05),血红蛋白浓度(Hb)、血液pH、心输出量及氧耗量虽无明显的差异性改变,但它们在4 500 m处的绝对值是增加的。在相同海拔,藏羊的Hb明显低于移居羊(P<0.05),4 500 m时藏羊的动脉血氧饱和度(Sao2)及组织摄氧量显著高于移居羊(P<0.05)。表明藏羊在急性低氧时表现出的高Sao2及高组织摄氧量,低Hb、低pH是它适应高原低氧的生理基础。

Effect of Acute Hypoxia on the Parameters of Blood Gas in Tibetan Plateau Sheep

Tibetan sheep(Ovis aries) have been living in the Qinghai-Tibetan plateau for a long time and are considered to be adapted to high altitude.In order to explore the possible mechanisms of adaptation to acute hypoxia,we measured the parameters of blood gas in 7 awake male Tibetan sheep and 5 awake male emigrated sheep that were transported to Xining(2 260 m above sea level) after being captured at 3 000 m in a decompression chamber(simulated altitudes of 0 m,2 300 m and 4 500 m).The cardiac output was measured by a thermo dilution technique.Arterial and mixed venous blood pH,partial pressure of oxygen(Po_2),partial pressure of carbon dioxide(Pco_2) and oxygen saturation(So_2) were measured with a blood gas analyzer with an EG7cartridge.Oxygen consumption was calculated by Fick's methods.The results showed that when the animals were exposed to simulated altitudes at 0,2 300 and 4 500?m,So_2,Po_2 and Pco_2 decreased significantly in tandem with altitude elevation in both kinds of sheeps(P<0.05),while Hb,pH(an index of ventilate responses),the cardiac output and the oxygen consumption did not change significantly.At the same altitude,Hb was significantly lower in Tibetan sheep compared to emigrated sheep(P<0.05).At 4 500 m,Sao_2 and tissue oxygen intake were significantly higher in Tibetan sheep compared to emigrated sheep(P<0.05).In summary,high Sao_2 and tissue oxygen intake and low Hb and pH in Tibetan sheep are considered to be characteristics of adaption to acute hypoxia.