Richards C D
Br J Anaesth. 1983 Mar;55(3):201-7. doi: 10.1093/bja/55.3.201.
This article reviews the actions of general anaesthetics on synapses in the mammalian central nervous system. It is shown that during general anaesthesia, anaesthetics act primarily on the chemical transmission process itself and do not affect the conduction of impulses in nerve axons or change the electrical excitability of neurones. Virtually all general anaesthetics depress excitatory synaptic transmission at concentrations required for surgical anaesthesia but some, notably the barbiturates, also increase the intensity of inhibitory synaptic transmission. Detailed analysis has found that small concentrations of barbiturates increase the amount of inhibitory transmitter released but decrease the amount of excitatory transmitter released. In addition to these effects on the neurosecretory process, anaesthetics directly affect the sensitivity of the postsynaptic receptors to transmitter substances, although the effects vary between anaesthetics and receptors. It is concluded that general anaesthesia results from a summation of a number of effects which together tend to depress the excitability of the CNS as a whole.
本文综述了全身麻醉药对哺乳动物中枢神经系统突触的作用。研究表明，在全身麻醉期间，麻醉药主要作用于化学传递过程本身，并不影响神经轴突中冲动的传导，也不改变神经元的电兴奋性。实际上，所有全身麻醉药在外科麻醉所需浓度下都会抑制兴奋性突触传递，但有些麻醉药，尤其是巴比妥类药物，还会增强抑制性突触传递的强度。详细分析发现，低浓度巴比妥类药物会增加抑制性递质的释放量，但会减少兴奋性递质的释放量。除了对神经分泌过程的这些影响外，麻醉药还直接影响突触后受体对递质的敏感性，尽管不同麻醉药和受体的影响有所不同。得出的结论是，全身麻醉是多种效应的总和，这些效应共同倾向于抑制整个中枢神经系统的兴奋性。
