Tetrahydroberberine blocks membrane K+ channels underlying its inhibition of intracellular message-mediated outward currents in acutely dissociated CA1 neurons from rat hippocampus.
In the patch-clamp perforated whole-cell recording mode, tetrahydroberberine (THB), a novel dopamine (DA) receptor antagonist, inhibits not only DA-induced outward K+ currents, but also acetylcholine-, caffeine- or strychnine-induced outward current. However, THB does not affect either GABA- or glycine-induced Cl- currents, or non-NMDA receptor agonist-induced cation currents. As expected for a K+ channel blocker, THB evokes a downward current deflection accompanied by a decrease of conductance. It is concluded that the direct blockade of membrane K+ channels by THB underlies its inhibition of intracellular message-mediated outward currents.
Wu
J
J
Department of Neurology, University of New Mexico School of Medicine, Albuquerque 87131, USA. wujie@unm.edu
Jin
G Z
GZ
D000818:Animals; D001599:Berberine / Q000031:analogs & derivatives* / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology*; D004594:Electrophysiology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D051381:Rats; D017208:Rats, Wistar
D018492:Dopamine Antagonists; D026902:Potassium Channel Blockers; D001599:Berberine; C004645:canadine