Expression of an atrial G-protein-activated potassium channel in Xenopus oocytes

N. Dascal*, N. F. Lim, W. Schreibmayer, W. Wang, N. Davidson, H. A. Lester

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Injection of rat atrial RNA into Xenopus oocytes resulted in the expression of a guanine nucleotide binding (G) protein-activated K+ channel. Current through the channel could be activated by acetylcholine or, if RNA encoding a neuronal 5HT1A receptor was coinjected with atrial RNA, by serotonin (5HT). A 5HT-evoked current (I5HT) was observed in oocytes injected with ventricle RNA fractions (of 2.5-5.5 kb) and 5HT1A receptor RNA. I5HT displayed strong inward rectification with very little conductance above the K+ equilibrium potential, was highly selective for K+ over Na+, and was blocked by 5-300 μM Ba2+. I5HT was suppressed by intracellular injection of the nonhydrolyzable analog of GDP, guanosine 5′-[β-thio]diphosphate, but not by treatment with pertussis toxin (PTX), suggesting coupling of the receptor to the G-protein-activated K+ channel via a PTX-insensitive G protein, possibly endogenously present in the oocyte. Coexpression of the α subunit of a PTX-sensitive G protein, Gi2, rendered I5HT sensitive to PTX inhibition. Native oocytes displayed a constitutively active inwardly rectifying K+ current with a lower sensitivity to Ba2+ block; expression of a similar current was also directed by atrial or ventricle RNA of 1.5-3 kb. Xenopus oocytes may be employed for cloning of the G-protein-activated K+ channel cDNA and for studying the coupling between this channel and G proteins.

Original languageEnglish
Pages (from-to)6596-6600
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume90
Issue number14
StatePublished - 15 Jul 1993

Funding

FundersFunder number
National Institute of Mental HealthP50MH049176
National Institute of General Medical SciencesR01GM029836

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