Abstract
Threshold concentrations of lysophosphatidic acid (LPA) or acetylcholine (ACh) induce pertussis toxin (PTX)-sensitive rapid desensitization of responses to LPA in Xenopus oocytes. To demonstrate that threshold [LPA] rapidly activates Gi/o proteins, we used the G protein-activated K+ channel (GIRK) as a reporter. Low [LPA] induced IK+ in <3 s of the agonist addition with little or no activation of chloride current. Depletion of Galphao/Galphao1 each decreased the LPA-induced IK+ by approximately 40-50%, while PTX completely abolished it. This is the first direct evidence showing the activation of GIRK by LPA, and the involvement of G proteins of the Go family in rapid desensitization of LPA responses.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Electrophysiology
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G Protein-Coupled Inwardly-Rectifying Potassium Channels
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GTP-Binding Protein alpha Subunits, Gi-Go / metabolism
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GTP-Binding Proteins / drug effects
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GTP-Binding Proteins / metabolism*
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Lysophospholipids / pharmacology*
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Membrane Potentials
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Microinjections
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Oocytes
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Potassium / metabolism
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Potassium Channels / agonists*
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Potassium Channels / genetics
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Potassium Channels, Inwardly Rectifying*
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RNA, Messenger
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Rodentia
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Xenopus
Substances
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G Protein-Coupled Inwardly-Rectifying Potassium Channels
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Lysophospholipids
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Potassium Channels
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Potassium Channels, Inwardly Rectifying
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RNA, Messenger
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GTP-Binding Proteins
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GTP-Binding Protein alpha Subunits, Gi-Go
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lysophosphatidic acid
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Potassium