急性低氧对家兔血压心率微血管反应性及自由基的影响

EFFECTS OF ACUTE HYPOXIA ON THE BLOOD PRESSURE HEART RATE,MICROVESSELS RESPONSE AND FREE RADICAL IN RABBIT

目的 :探讨不同急性低氧下的血压、心率、微血管反应性和自由基的影响。方法 :实验采用家兔人工吸入含氧量为 12 .5 %和 8.5 %氮氧混合气体 (模拟 4 0 0 0m和 6 5 0 0m高原急性低氧 )。急性低氧时间分别为 5、10、15、2 0min ,观察血压、心率、微血管反应性和自由基影响。结果 :①急性低氧 5min时收缩压略有升高 ,以后变为降低 ;舒张压在急性低氧 2 0min后明显降低 (P <0 .0 5 ) ;②心率随急性低氧时间的延长变慢 ,尤其含氧量 8.5 %急性低氧组明显 (P <0 .0 5 )。③眼结膜微血管管径随急性低氧时间延长呈现扩张 (P <0 .0 5 ) ,血细胞流速减慢 (P <0 .0 5 ,P <0 .0 1)。④急性低氧 2 0min后SOD活力明显降低 (P <0 .0 5 ) ,MDA含量升高 (P <0 .0 5 )。结论 :急性低氧可使血压降低 ,心率减慢 ,微血管管径变大和血细胞流速减慢 ,同时体内自由基产生增加。

Aim: To study the effects of different acute hypoxia on blood pressure, heart rate and microvessels and free radical in rabbits. Methods: The experiment model was carried out with acute hypoxia on two groups of rabb its ,using artificial inspiration 12.5% O 2 and 87.5% N 2,8.5% O 2 and 91.5% N 2(equivalent to altiudes of some 4 000 m and 6 500 m) keeping hypoxia for 5 、10、15、20 min.During the course of it,the changes of blood pressure, heart rate and microvessels response, superoxid dismutase(SOD), malondialdehyde (MDA) were recorded accordingly. Results: ①systolic pressure was sli ghtly up, then down in 5 mins. Diastolic pressure was significantly down(P<0 .05) in 20 min.②Heart rate showed reduced and prolonged ,particularly in 8.5% hypoxia group(P<0.05). ③Vas bores of microvessles expanded (P<0.05) an d the blood stream became slow gradually (P<0.05,P<0.01) in following ac ute hypoxia time.④SOD was significantly down(P<0.05),MDA was significantly increased (P<0.05) in 20mins. Conclusion: Acute hypoxia cou ld cause the blood pressure and heart rate to decrease, vas bore of microvessle to expand,the blood circulation to slow down and free radicals would increase.