机体不同状态下高压氧暴露后对脑微血流动力作用的差异性

目的 :探讨正常及急性脑缺血损伤动物高压氧暴露后大脑微循环血流动力作用的变化。方法 :成年沙土鼠 61只 ,随机分为 0 .1MPa、0 .2MPa、0 .2 5MPa高压氧暴露组 ,脑缺血损伤组和对照组。实验时动物用urethane麻醉 ,在颅骨顶开窗 ,暴露软脑膜。用阻断双侧颈总动脉造成脑缺血损伤。用LMB 1检测软脑膜细动静脉管径和流速 ,用LDF 3检测脑皮质局部血流量。动物在小型氧舱进行了实验暴露。结果 :动物在 0 .2MPa氧暴露后软脑膜细动脉比暴露前收缩 10 .1% ,细动脉血流速度比高压氧暴露前减慢 0 .58mm/s ,细静脉流速比高压氧暴露前减慢 0 .2 9mm/s ,大脑皮质血流量减少 3 4 % ,有非常显著差异 (P <0 .0 1)。而脑缺血损伤动物暴露于 0 .2 5MPa高压氧 60min ,细动脉可在颈动脉再灌流后血流速度得到一定改善的基础上净增 0 .85mm/s ,细静脉血流速度增加 0 .3 1mm /s ,脑皮质血流量在高压氧暴露后可恢复到或接近脑损伤前水平。单纯脑缺血组在实验观测期间软脑膜细动静脉血液速度和脑皮质血流量均明显减少 (P <0 .0 1)。结论 :机体不同状态 (脑缺血性损伤与正常机体 )高压氧暴露后脑血流动力作用出现的差异 ,可能与机体在不同状态下对氧的反应与需求有关。

Difference of The Cerebral Microcirculatory Hemodynamics After Hyperbaric Oxygen in Animals with Different Body State

To probe changes of the cerebral microcirculatory hem odynamics after hyperbaric oxygen(HBO) in normal and cerebral ischemic injury an imals.Method: 61 gerbils were divided randomly into 0.1 MPa,0.2 MPa,0. 25 MPa HBO exposure groups and the cerebral ischemic injury and control groups.A nimals were anesthetized by urethane.The skull was cut and pia mater was exposed .Ischemic cerebral injury resulted from carotids were blocked.The caliber and mi crocirculatory hemodynamics were determined by LMB 1 and LDF 3 in the cerebra l microvessels.The animals were exposed in HBO chamber during experiment.Results: After at 0.2 MPa HBO exposure,cerebral microvessels con tracted 10.1% in normal animals,the rate of blood flow separately reduced 0.58 m m/s and 0.29 mm/s in arteriolar and venulae,and cerebral blood flow volume decre ased 34%.They were significantly decreased as compared with before HBO exposure. However,the rate of blood flow separately increased 0.85 mm/s and 0.31 mm/s afte r at 0.25 MPa HBO exposure in animals with cerebral ischemic injury in the basis of reperfusion.The volume repaired to normal( P<0.01 ).But the hemodynamics d ecreased in the animals with cerebral ischemic injury without HBO trentment( P< 0.01 ).Conclusion: The difference of cerebral hemodynamics after HBO ex posure may be relation of body for HBO reacting and need in animals with differe nt body states(cerebral ischemic injury and normal animals).