The effect of volatile anaesthetics on synaptic release and uptake of glutamate

1. Volatile anaesthetics seem to exert their effects on several parts of the neuronal conducting system. 2. The effect on synaptic excitation seems to be quantitatively the most important (Berg-Johnsen and Langmoen, Acta Physiol. Scand. 128, 1986, 613-618) as 1 minimum alveolar concentration (MAC) of isoflurane reduces the activity in thin unmyelinated afferent fibres by 18%, excitatory synapses by 27% and postsynaptic neurones by 24%. 3. The reduction in excitatory synaptic transmission is caused by a decreased amount of transmitter glutamate in the synaptic cleft caused by a reduced release and increased uptake of glutamate in the presynaptic terminals (Larsen et al., Brain Res. 663, 1994, 335-337; Larsen et al., Br. J. Anaesth. 78, 1997, 55-59).