Fig. 6. Effects of 0.75 MAC sevoflurane (1 MAC is defined to be the minimum alveolar concentration of an inhaled anesthetic required to suppress movement in response to noxious stimulation in 50% of subjects) in the absence and presence of 100 μm bicuculline. A concentration of 100 μm bicuculline abolished the depression of neuronal network activity by 0.26 mm (corresponding to 0.75 MAC) sevoflurane almost completely (from 49.61 ± 3.41% in the absence to 2.87 ± 5.13% in the presence of bicuculline; ***  P < 0.001,  t test, n = 10). This result points to enhanced synaptic inhibition mediated  via γ-aminobutyric acid type A receptors being the predominate mechanism to cause the depressant effects of 0.75 MAC sevoflurane in neocortical slices.