Fig. 7.
Suppression of slowly activating delayed rectifier K+ current (IKs) by desflurane. (A) IKs recorded during 2,000-ms depolarizing voltage steps to test potentials of −40 to +50 mV applied from a holding potential of −50 mV, before and after a 5-min exposure to 12% desflurane (DES). Single exponential fit of IKs tail currents elicited on return to −50 mV after a depolarizing step to +50 mV, with a time constant (τ) as indicated in this example (inset). It was confirmed in different sets of experiments that the inhibitory effect of 6 and 12% desflurane on IKs, repetitively (every 8 s) activated by 2,000-ms depolarizing steps to +40 mV, reached steady-state level within 1 min after the application and was fully reversed within 2 min after the washout (data not shown). (B) Current–voltage relationships for IKs tail currents in the absence and presence of 6 and 12% desflurane. The smooth curves through the data points represent the least-squares fit of the Boltzmann equation. (C) The maximal amplitude of IKs (IKs,max), obtained by Boltzmann fits of IKs tails currents recorded in control and in the presence of 6 and 12% desflurane. *P< 0.05 compared with the control.