Assessment of the effect of etomidate on voltage-gated sodium channels and action potentials in rat primary sensory cortex pyramidal neurons

Abstract

Although it is known that general anesthetics can suppress cortical neurons׳ activity, the underlying mechanisms are still poorly understood, especially the kinetic changes of voltage-gated Na(+) channels, which are mostly related to neuronal excitability. Some general anesthetics have been reported to affect the voltage-gated Na(+) channels in cell culture derived from humans and animals. However no one has ever investigated the effects of etomidate on voltage-gated Na(+) channels in pyramidal neurons using a brain slice. The present study uses a whole cell patch-clamp technique to investigate the changes of voltage-gated Na(+) channels on primary somatosensory cortex pyramidal neurons under the influence of etomidate. We found that etomidate dose-dependently inhibited Na(+) currents of primary somatosensory cortex pyramidal neurons, while shifted the steady-state inactivation curve towards the left and prolonged the recovery time from inactivation. Conversely, etomidate has no effects on the steady-state activation curve. We demonstrated the detailed suppression process of neural voltage-gated Na(+) channels by etomidate on slice condition. This may offer new insights into the mechanical explanation for the etomidate anesthesia. Finding the effects of anesthetics on primary somatosensory cortex also provides evidence to help elucidate the potential mechanism by which tactile information integrates during general anesthesia.

Keywords: Action potentials; Etomidate; General anesthesia; Primary somatosensory cortex; Voltage-gated ion channels.