Fig. 2.
Effects of desflurane on hyperpolarization-activated cation current (If). (A) Superimposed current traces of If activated during 2,000-ms hyperpolarizing voltage steps applied from a holding potential of −40 mV to test potentials of −50 through −140 mV, before (control) and after a 5-min exposure to 12% desflurane (DES) and after 5 min of the washout. Voltage-clamp protocol is indicated above the control current traces. It was confirmed in different sets of experiments that the effect of 6 and 12% desflurane on If, repetitively (every 8 s) activated by hyperpolarizing steps to −130 mV, reached steady-state level within 1–2 min after the application, which was returned to the baseline level within 2 min after washout of desflurane (data not shown). (B) If conductance (gf)–voltage relationships recorded in the absence (control) and presence of 6 and 12% desflurane. The smooth curves through the data points represent the least-squares fit of the Boltzmann equation. (C) Maximal If conductance (gf,max) obtained by fitting conductance–voltage relationship to the Boltzmann equation shown in B. *P < 0.05 compared with the control.