Effect of sevoflurane on the voltage-dependent sodium currents in a Lymnaea neuron

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17591641
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Anesthesiology/Resuscitation studies
• Research Institution: University of Miyazaki
• Principal Investigator: ONIZUKA Shin University of Miyazaki, Faculty of Medicine, Associate Professor, 医学部, 助手 (20264393)
• Project Period (FY): 2005 – 2006
• Keywords: Sevoflurane / Internal perfusion / Sodium currents / リドカイン / ナトリウムチャネル

Research Abstract

Background : The voltage-dependent sodium currents (INa^+) are related to neuron excitability and anesthesia. To clarify the anesthetic mechanism of sevoflurane affecting INa^+, the effects of sevoflurane and lidocaine on INa^+ were compared using a neuron from Lymnaea stagnalis.
Methods : The effects of sevoflurane and lidocaine on the membrane potential and INa+ were measured using current clamp and whole cell patch-clamp configuration. Sevoflurane was perfused either extra-cellularly or intra-cellularly. The amplitude of action potential, current voltage curves, and steady-state inactivation curves for INa+ were measured following in external and internal perfusion of sevoflurane.
Results : External perfusion with sevoflurane suppressed the amplitude of the action potential [61.8 ± 7.6 (mV) in the controls, 43.8 ± 7.1 at 0.4 mM, 4.8 ± 3.6 at 2 mM, and 0.9 ± 0.8 at 4 mM], and INa^+ [80 ± 11% at 0.4 mM, 59 ± 12 % at 2 mM, and 48 ± 12 % at 4 mM] in a concentration-dependent manner. However, with internal perfusion, sevoflurane did not suppress these parameters. Conversely, internal perfusion of lidocaine suppressed INa+. The steady-state inactivation curves were not shifted by either external or internal perfusion of sevoflurane as lidocaine.
Conclusion : Sevoflurane acts as an extra-cellular plug to suppress the voltage-dependent sodium currents.