L-NAME在大鼠失血性低血压期间对多巴胺与去甲肾上腺素升压效应的影响

目的：观察大鼠失血性低血压期间，一氧化氮（NO）和一氧化氮合酶减少对多巴胺（DA）与去甲肾上腺素（NE）升压效应的影响。方法；戊巴比妥钠麻醉的SD大鼠24只，随机分为DA实验组与对照组各5只，NE实验组与对照组各7只。实验组失血前静脉注射NG－nitro－L－argininemethylester（L－NAME，1mg／kg体重），回输血液后静脉注射L－arginine（L－Arg，100mg／kg体重），对照组不作任何处理。股动脉抽血使平均动脉压（MAP）降至5．0kPa左右，维持120min，于低血压期间，每隔30min，及回输血液后10min，静脉注射L－Arg后10min等时间点，静脉注射DA（20μg／kg体重）或NE（10μg／kg体重）。结果：经L－NAME处理的大鼠，存活时间延长，回输血液后，BP基本恢复至失血前水平，无论在低血压期间或血液回输后，对DA、NE的升压反应均增强，实验组MAP回升值明显高于对照组（P＜0．05），L－Arg可抑制此作用。心率（HR）反应在L－NAME处理鼠与对照鼠之间无差异。结论。在重度失血性低血压期间，L－NAME可以增强血管对DA、NE等缩血管药物的敏感性，在动物的存活和血管张力的调节方面起有益作用。

EFFECT OF L-NAME ON BACKWARD PRESSOR OF INDOPAMINE AND NOREPINEPHRINE DURING HEMORRHAGIC HYPOTENSION IN RATS

Objective: To observe the effects of nitric oxide and nitric oxide synthetase on the pressor response to dopamine (DA)and norepinephrine (NE )during hemorrhagic hypotension in anesthetized rats.Methods: Twenty-four adults SD rats were divided randomly into four groups, i. e. DA experimental group and DA as control group (five cases, respectively), NE experimental group and NE as control group (seven cases, respectively ). NG-nitro-L-arginine methyl ester (L-NAME, 1mg/kg, iv ) was administered 10 min before bleeding and L-arginine (L-Arg, 100mg/kg,iv)was administered 20 min after transfusion in the two experimental groups. The control groups weren't treated. The mean arterial blood pressure(MAP)was reduccd to 5. 0kPa or so by drawing blood from the femoral artery and maintained constant 120 min. At 30, 60, 90, 120 min after L-Arg,DA or NE was infused the arterial blood pressure and heart rate were recordcd. Results: Thc survival time was prolonged in the L-NAME treated rats and the value of MAP was recovered to the level of probleeding after transfusion. Whether in the hypotension period or after transfusion, the pressor action of DA or NE was enhanced. The recovered value of MAP was significantly increased in L-NAME treated rats than that in contro1 group(P<0. 05). The response could be inhibited by L-Arg. There are not significant difference of the response of heart rate between L-NAME trented rats and control rats. Conclusion: L-NAME may enhance the vascular sensitivity to vasoconstrictor agents and play a beneficial role in the animal survival and recovery of vascular tension during severe hemorrhagic hypotension.