Fig. 5. Acute effects of sevoflurane on hippocampal long-term potentiation (LTP). (A ) A representative experiment showing the time course of changes of field excitatory postsynaptic potential (fEPSPs) slope caused by high-frequency stimulation (HFS) and by subsequent application of sevoflurane. Thirty minutes after HFS, 2.1% sevoflurane was added to the bath for 20 min (horizontal bar ). (B ) A representative experiment with 4% sevoflurane. After washout of sevoflurane, the fEPSP slope remained near baseline. At 100 min, a second HFS pulse resulted in LTP again. (C ) Group data: S2, sevoflurane at 2.1%; W2, after 30 min washout of 2.1% sevoflurane; S4, sevoflurane at 4%; W4, after 30 min washout 4% sevoflurane; LTP #2, in two of four experiments using 4% sevoflurane, LTP was evoked again. *P < 0.01 vs.  baseline (pre-HFS). (D ) Group data of percent change in paired pulse ratio (PPR) of the fEPSP slope at 10, 20, and 30 min after 4% sevoflurane exposure. *P < 0.01 vs.  PPR before sevoflurane exposure.