Fig. 4. Effect of isoflurane on miniature excitatory postsynaptic currents (mEPSCs). mEPSCs were recorded at −70 mV, in the presence of tetrodotoxin (0.5 μm). ( A ) The consecutive traces of mEPSCs before ( left ) and during ( right ) application of isoflurane (Iso; 3 min). ( B ) Cumulative distributions of interevent intervals and amplitudes of mEPSC, before ( straight line ) and under ( dotted line ) the action of isoflurane. Data were constructed from continuous recording for 30 s each. Isoflurane did not affect the distributions of interevent intervals and amplitudes. ( C ) The frequency and mean amplitude under the action of isoflurane, relative to those in the control. Isoflurane affected neither the frequency nor mean amplitude of mEPSCs (n = 8).