Figure 4

The increase in spontaneous inhibitory postsynaptic current (sIPSC) frequency by esmolol in neurons of the caudal part of the spinal trigeminal nucleus (Sp5c). (A) The membrane current recording of an Sp5c neuron. Esmolol was applied at the horizontal bar. (B) Traces showing evoked IPSC (eIPSC) waveforms (average of eight consecutive traces) evoked by stimulation before (1; left), during (2; middle) and after (3; right) esmolol application in the Sp5c. 1-3 were sampled at points 1-3 in A. (C) 1-3 are time-extended traces taken at points 1-3 in the trace in A. (D) and (E) Summary of the effects of esmolol on eIPSC amplitude and sIPSC frequency, respectively. *, P < 0.05; Mann-Whitney's U-test. (F) The time course of the changes with esmolol in sIPSC frequency (thick line) and eIPSC amplitude (thin line) that were simultaneously recorded. The abscissae of these graphs are identical (time).