低氧适应对家兔脑血流调节的影响

本实验用电磁血流量法观察了低氧适应对家兔脑血流(CBF)调节的影响。结果表明,高CO_2和低O_2高CO_2时,适应组CBF改变不明显,对照组CBF明显增加(p<0.01)。两组脑脊液pH(pH_(CSF))均明显降低(p<0.05和p<0.01)。对照组低O_2高CO_2时的CBF比单独高CO_2增加更多。低CO_2、低O_2低CO_2及低O_2时,CBF和pH_(CSF)均接近于安静值。以低pH值脑脊液(CSF)脑内灌注,对照组CBF趋于增加,适应组不增加。将CO_2饱和的人工CSF用于局部脑表面,适应组脑膜微血管无明显扩张,对照组明显扩张(p<0.01)。该结果提示,低氧适应家兔脑血管和CBF对脑细胞外液H~ 和/或对低O_2的反应降低。

EFFECTS OF ADAPTATION TO HYPOXIA ON REGULATION OF CEREBRAL BLOOD FLOW IN RABBITS

Effects of adaptation to hypoxia on regulation of cerebral blood flow (CBF) were investigated in rabbits. The results were as follows: (1) During hypercapnia (5% CO2) or hyper-capnia combined with hypoxia (10% O2), CBF increased in the control group (p<0.05, p<0.01) but was not altered in adapted group. Cerebrospinal fluid pH(pHCSF) was reduced (p<0.01) in both groups. CBF was higher during hypercapnia combined with hypoxia than during hypercapnia only. (2) During hypocapnia and/or hypoxia, CBF and pHCSF approximated to the values in rest. (3) Perfusion with artificial CSF of low pH induced greater increase in CBF in the control group than in adapted group. (4) The artificial CSF saturated with CO2 induced a greater dilation of cerebral microvessels in the control group than in adapted group. The results suggested that adaptation to hypoxia might reduce the responses of cerebral vessels and CBF to H of cereurai extracelluar fluid and /or to hypoxia.