高原鼠兔氧比传导特征的实验研究

EXPERIMENTAL STUDY ON SPECIFIC CONDUCTANCE OF OXYGEN (MO_2-SC) IN PIKA

本实验采用国外新近提出的一项能综合评价机体气体交换系统中各氧降阶差时运氧能力的适应水平高低的重要指标──氧比传导（ＭＯ２－ＳＣ），研究了高原鼠兔气体交换系统运氧能力的低氧适应特征及规律。结果表明，对照条件下，在吸入气（Ｉ）至肺泡气（Ａ）（Ｉ→Ａ）、Ａ至动脉血（ａ）（Ａ→ａ）、ａ至混合静脉血（ｖ）（ａ→ｖ）及Ｉ→ｖ各阶差中，以Ａ→ａ的ＭＯ２－ＳＣ运氧能力最大。低氧１５ｍｍ后，Ｉ→Ａ及ａ→ｖ的ＭＯ２－ＳＣ均显著升高，并以Ｉ→Ａ增加最为显著，该水平运氧能力是对照的２倍，增长１２０．９％；而Ａ→ａ及Ｉ→ｖＭＯ２－ＳＣ变化无显著性差异。低氧３０ｍｉｎ时，Ｉ→Ａ的ＭＯ２－ＳＣ继续显著增长，运氧能力是对照的２．７倍，增长１７０．７％，其余３个氧降阶差的ＭＯ２－ＳＣ无显著性改变。以上结果表明，高原鼠兔低氧代偿贮备较大，尤以肺泡气至动脉血阶差最为重要，而通气氧传导能力的增强也是高原鼠兔低氧适应的主要原因。

MO2-SC, a good index to evaluate the capacity of transporting oxygen at four levels of oxygen cascades, i. e,. inspired air to alveolar gas (I→A), A to arterial blood (A→a), a to mixed venous blood (a→v) and I to v (I→v), was studied in 15 pikas (Ochotona curzoniae) native to high altitude. It was found that under control condition, MO2→SC of A→a was the highest among the four MO2-SCs (P<0.01). After exposure to hypoxia for 15 min, MO2-SC of I→A and a→v rose significantly (P<0.01, P≤0.05, respectively) with 2-fold (120.9%) increase in MO2-SC of I→A as compared with control; while those of A→a and i→v didn't change significantly (P>0.05). After exposure to hypoxia for 30min, MO2-SC of I→A increased continuously (P<0.01) by 2.7-fold or 170.7% as compared with control, while the rest three levels did not change significantly. The results suggest that the pika has a large compensatory reserve to hypoxia at four MO2-SCs, especially at A→a level and the strong ventilation response was also the main factor for pika to adapt to hypoxia well.