Propofol suppresses a hyperpolarization-activated inward current in rat hippocampal CA1 neurons.
We examined the effect of propofol and thiopental, intravenous anesthetics, on the hyperpolarization-activated inward current (I(H)), whose functional role on the neuronal activity has been evaluated. Whole-cell recordings of I(H) evoked by hyperpolarizing step pulses were taken from hippocampal CA1 neurons in rat brain slices. Propofol reduced I(H) current in a dose-dependent manner. However, thiopental had no significant effect on the activation of I(H). According to the functional role of I(H), the suppression of I(H) should result in a reduction of neuronal activity. We suggest that the effectiveness of propofol as an anticonvulsant or an antiemetic is associated with the blockade of the I(H) channel.
Funahashi
M
M
Department of Oral Physiology, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8525, Japan. mfuna@md.okayama-u.ac.jp
Higuchi
H
H
Miyawaki
T
T
Shimada
M
M
Matsuo
R
R
D018686:Anesthetics, Intravenous / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007473:Ion Channels / Q000187:drug effects* / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D010599:Pharmacokinetics; D015742:Propofol / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000187:drug effects* / Q000378:metabolism; D013874:Thiopental / Q000493:pharmacokinetics
D018686:Anesthetics, Intravenous; D007473:Ion Channels; D011963:Receptors, GABA-A; D013874:Thiopental; D015742:Propofol