Fig. 4. The effects of sevoflurane on paired pulse facilitation (PPF). (  A ) Sample recordings obtained at the control period, during the maximal effect of 0.41 mm sevoflurane (Sev), and after washout. (  B ) The graph shows the time course of the effects of sevoflurane on PPF. PPF (pulse interval 60 ms) was recorded in the presence of 0.41 mm sevoflurane (  solid bar ) in normal artificial cerebrospinal fluid. Sevoflurane increased PPF gradually, and PPF returned to the control after the washout within 30 min. (  C ) A bar graph summarizes the effect of sevoflurane on PPF. Sevoflurane increased PPF of field excitatory postsynaptic potentials amplitude in a concentration-dependent manner (**  P < 0.01  vs. 0.23 mm sevoflurane, ***  P < 0.001  vs. 0.41 mm sevoflurane; n = 6). Data are expressed as mean ± SD.