吸入麻醉药对兔肾交感神经活动的影响

目的比较吸入麻醉药对交感神经活动和血液动力学的影响。方法18只兔被随机分为三组:安氟醚组、异氟醚组和地氟醚组。兔麻醉、肌松和人工通气后,暴露肾交感神经并记录其电生理活动。分别吸入呼气末浓度为0.8%、1.6%、2.4%、3.2%安氟醚,0.6%、1.2%、1.8%、2.4%异氟醚,或3.0%、6.0%、9.0%、12.0%地氟醚。结果交感神经活动在兔吸入2.4%安氟醚、0.6%异氟醚和6.0%地氟醚时分别增加到44%、36%和32%,当进一步增加吸入麻醉药的浓度则抑制肾交感神经活动。血压随着吸入麻醉药浓度的增加不断下降而心率除了2.4%异氟醚诱发心率减慢外无明显变化。结论安氟醚、异氟醚和地氟醚具有双向作用,低浓度兴奋交感神经,高浓度抑制交感神经活动和降低血压。

Effects of inhalational anesthetics on sympathetic nerve activity in rabbits

Objective To investigate the effects of inhalational anesthetic agents on sympathetic nerve activity and hemodynamics.Methods Rabbits were anesthetized,paralyzed and artificially ventilated.Renal sympathetic nerve was exposed and prepared for recording the electrical activity.Eighteen rabbits were divided into three groups.Each inhalational agent was delivered to 6 rabbits at the following end tidal concentrations: enflurane 0.8%,1.6%,2.4% and 3.2%,isoflurane 0.6%,1.2%,1.8% and 2.4%,desflurane 3.0%,6.0%,9.0% and 12.0% respectively.Results Concentrations of 2.4% enflurane,0.6% isoflurane,and 6.0% desflurane increased maximally the sympathetic activity up to 44%,36% and 32% respectively.While sympathetic activity was depressed by higher concentrations of inhalational agents.Enflurane,isoflurane and desflurane caused a concentration dependent depression in mean arterial pressure without significant changes in heart rate except with 2.4% isoflurane.(Conclusion)The effects of enflurane,isoflurane and desflurane are biphasic:excitation at lower concentrations,and depresssion of sympathetic activity and arterial pressure at higher concentrations.