Fig. 3. Miniature excitatory postsynaptic currents, in mechanically isolated ventrolateral preoptic nucleus neurons recorded in the presence of tetrodotoxin (TTX) or Cd2+, are not sensitive to propofol. ( A–C ) Effects of propofol on spontaneous excitatory postsynaptic currents (sEPSCs) recorded in the absence and presence of 1 μm tetrodotoxin. ( A ) Original traces of spontaneous EPSCs obtained at times indicated by lowercase letters in B . ( B ) Time course of changes in sEPSC frequency. ( C ) Cumulative probability plots of intervals between sEPSCs show that the sharp effect of propofol disappears in the presence of tetrodotoxin (n = 5). Insets are mean changes (± SEM): ** P < 0.01 by paired t test for propofol versus prepropofol. ( D–F ) Effects of propofol on sEPSCs recorded in the absence and presence of 100 μm Cd 2+. (D ) Original traces of sEPSCs. ( E ) Time course of changes in sEPSC frequency. ( F ) Cumulative probability plots of intervals between sEPSCs: As indicated by inset histograms (mean ± SEM, n = 5), the effect of propofol was no longer significant in the presence of 100 μm Cd2+. ** P < 0.01 by paired t test for propofol versus prepropofol values.