Langmoen I A, Larsen M, Berg-Johnsen J
Institute for Surgical Research, University of Oslo, Norway.
Eur J Anaesthesiol. 1995 Jan;12(1):51-8.
The mechanisms by which volatile anaesthetics act in the central nervous system are reviewed. The main cellular targets are excitatory synapses and the cell membrane of the neuronal cell body/dendrite, although there also appears to be a significant effect on thin unmyelinated fibres. Experiments quantifying these effects have shown that 1 MAC isoflurane reduces the activity in afferent fibres by 18%, excitatory synapses by 27% and postsynaptic neurones by 24%. Two important effects observed when recording from individual neurones are hyperpolarization of the cell membrane by an enhanced potassium conductance and increased threshold for initiation of action potentials. Excitatory synaptic transmission is most probably reduced due to a decreased release of transmitter from presynaptic terminals. Antagonistic and biphasic effects are often seen, for instance depression of both inhibitory and excitatory transmission and depolarization-hyperpolarization of the postsynaptic membrane.
本文综述了挥发性麻醉药在中枢神经系统中的作用机制。主要细胞靶点是兴奋性突触以及神经元胞体/树突的细胞膜，不过对细的无髓鞘纤维似乎也有显著影响。量化这些效应的实验表明，1个最低肺泡有效浓度（MAC）的异氟烷可使传入纤维的活性降低18%，兴奋性突触降低27%，突触后神经元降低24%。在记录单个神经元时观察到的两个重要效应是，细胞膜因钾电导增强而发生超极化，以及动作电位起始阈值升高。兴奋性突触传递很可能因突触前终末递质释放减少而降低。经常会出现拮抗和双相效应，例如抑制性和兴奋性传递均受抑制，以及突触后膜的去极化 - 超极化。
