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XB-ART-9036
Proc Natl Acad Sci U S A 2001 May 22;9811:6482-7. doi: 10.1073/pnas.111447798.
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Mechanism underlying bupivacaine inhibition of G protein-gated inwardly rectifying K+ channels.

Zhou W , Arrabit C , Choe S , Slesinger PA .


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Local anesthetics, commonly used for treating cardiac arrhythmias, pain, and seizures, are best known for their inhibitory effects on voltage-gated Na(+) channels. Cardiovascular and central nervous system toxicity are unwanted side-effects from local anesthetics that cannot be attributed to the inhibition of only Na(+) channels. Here, we report that extracellular application of the membrane-permeant local anesthetic bupivacaine selectively inhibited G protein-gated inwardly rectifying K(+) channels (GIRK:Kir3) but not other families of inwardly rectifying K(+) channels (ROMK:Kir1 and IRK:Kir2). Bupivacaine inhibited GIRK channels within seconds of application, regardless of whether channels were activated through the muscarinic receptor or directly via coexpressed G protein G(beta)gamma subunits. Bupivacaine also inhibited alcohol-induced GIRK currents in the absence of functional pertussis toxin-sensitive G proteins. The mutated GIRK1 and GIRK2 (GIRK1/2) channels containing the high-affinity phosphatidylinositol 4,5-bisphosphate (PIP(2)) domain from IRK1, on the other hand, showed dramatically less inhibition with bupivacaine. Surprisingly, GIRK1/2 channels with high affinity for PIP(2) were inhibited by ethanol, like IRK1 channels. We propose that membrane-permeant local anesthetics inhibit GIRK channels by antagonizing the interaction of PIP(2) with the channel, which is essential for G(beta)gamma and ethanol activation of GIRK channels.

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Species referenced: Xenopus laevis
Genes referenced: kcnj1 kcnj12 kcnj2 kcnj3 kcnj6

References [+] :
Andrade, Blockade of neurotransmitter-activated K+ conductance by QX-314 in the rat hippocampus. 1991, Pubmed