Volatile anaesthetics inhibit a cyclic AMP-dependent sodium-potassium current in cultured sensory neurones of bullfrog.
1. Cultured dorsal root ganglion cells of the bullfrog were voltage-clamped in the whole-cell configuration. 2. An adenosine 3':5'-cyclic monophosphate (cyclic AMP)-dependent cationic inward rectifier (IH) was inhibited by bath application of enflurane (0.2-0.8 mM) and halothane (0.2-0.5 mM), which thereby induced an outward current at the resting potential, and a membrane hyperpolarization in unclamped cells. 3. The main effect of enflurane (0.5 mM) was to displace the steady-state IH activation curve to a hyperpolarizing direction by about 10 mV, as well as to reduce the maximum H-conductance to about 20%. 4. Forskolin (1-10 microM), which enhances IH by producing a depolarizing shift in the IH activation curve and increasing the maximum H-conductance, recruited IH even when the current had already been eliminated by enflurane (1 mM).
Tokimasa
T
T
Department of Physiology, Kurume University School of Medicine, Japan.
Sugiyama
K
K
Akasu
T
T
Muteki
T
T
D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D003864:Depression, Chemical; D004737:Enflurane / Q000494:pharmacology; D006221:Halothane / Q000494:pharmacology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects*; D011892:Rana catesbeiana; D015222:Sodium Channels / Q000187:drug effects*
D000777:Anesthetics; D015221:Potassium Channels; D015222:Sodium Channels; D005576:Colforsin; D004737:Enflurane; D000242:Cyclic AMP; D006221:Halothane