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Activation of atrial muscarinic K+ channels by low concentrations ofβγ subunits of rat brain G protein

  • Excitable Tissues Cand Central Nervous Physiology
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Abstract

Effects of G protein βγ subunits from rat brain on cardiac K+ channel was examined in single atrial cells of guinea-pig, using patch clamp techniques. We found that 10 pM concentration of rat brain βγ subunits preparation could activate the atrial muscarine receptor-gated K+ channel (IK.ACh). Neither the detergent, CHAPS, used to suspend βγ nor the boiled βγ preparation activated IK.ACh. Furthermore, preincubation of βγ subunits preparation in Mg2+-free solution, which easily inactivated α-GTP-γS, did not affect βγ-activation of IK.ACh. We concluded, therefore, that βγ subunits themselves can activate IK.ACh.

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References

  1. Pfaffinger PJ, Martin JM, Hunter DD, Nathanson, NH, Hille B (1985) GTP-binding proteins couple cardiac muscarinic receptors to a K channel. Nature 317, 536–538

    Article  CAS  PubMed  Google Scholar 

  2. Breitwieser GE, Szabo G (1985) Uncoupling of cardiac muscarinic and β-adrenergic receptors from ion channels by a guanine nucleotide analogue. Nature 317, 538–540

    Article  CAS  PubMed  Google Scholar 

  3. Kurachi Y, Nakajima T, Sugimoto T (1986) On the mechanism of activation of muscarinic K+ channels by adenosine in isolated atrial cells: involvement of GTP-binding proteins. Pflügers Arch 407, 264–274

    Article  CAS  PubMed  Google Scholar 

  4. Kurachi Y, Nakajima T, Sugimoto T (1986) Role of intracellular Mg2+ in the activation of muscarinic K+ channel in cardiac atrial cell membrane. Pflügers Arch 407, 572–574

    Article  CAS  PubMed  Google Scholar 

  5. Logothetis DE, Kurachi Y, Galper J, Neer EJ, Clapham DE (1987) The βγ subunits of GTP-binding proteins activate the muscarinic K+ channel in heart. Nature 325, 321–326

    Article  CAS  PubMed  Google Scholar 

  6. Yatani A, Codina J, Brown AM, Birnbaumer L (1987) Direct activation of mammalian atrial muscarinic potassium channels by GTP regulatory protein Gk. Science 235, 207–211

    Article  CAS  PubMed  Google Scholar 

  7. Codina J, Yatani A, Grenet D, Brown AM, Birnbaumer L (1987) The α subunit of Gk opens atrial potassium channels. Science 236, 442–445

    Article  CAS  PubMed  Google Scholar 

  8. Birnbaumer L, Brown AM (1987) G protein openings of K+ channels. Nature 327, 21

    Article  CAS  PubMed  Google Scholar 

  9. Kirsh GE, Yatani A, Codina J, Birnbaumer L, Brown AM (1988) The α subunit of Gk activates K+ channels of chick, rat and guinea pig. Am J Physiol 254, H1200-H1205

    Google Scholar 

  10. Logothetis DE, Kim D, Northup JK, Neer EJ, Clapham DE (1988) Specificity of action of G protein subunits on the cardiac muscarinic K+ channel. Proc Natl Aca Sci USA 85, 5814–5818

    Article  CAS  Google Scholar 

  11. Katada T, Oinuma M, Ui M (1986) Two guanine nucleotide-binding proteins in rat brain serving as the specific substrate of islet-activating protein, pertussis toxin. J Biol Chem 261, 8182–8191

    CAS  PubMed  Google Scholar 

  12. Katada T, Oinuma M, Kusakabe K, Ui M (1987) A new GTP-binding protein in brain tissues serving as the specific substrate of islet-activating protein, pertussis toxin. FEBES Lett 213, 353–358

    Article  CAS  Google Scholar 

  13. Codina J, Hildebrandt JD, Birnbaumer L (1984) Effects of guanine nucleotides and Mg on human erythrocyte Ni and Ns, the regulatory components of adenylyl cyclase. J Biol Chem 259, 11408–11418

    CAS  PubMed  Google Scholar 

  14. Jelsema CJ, Axelrod J (1987) Stimulation of phospholipase A2 activity in bovine rod outer segments by the βγ subunits of transducin and its inhibition by the α subunit. Proc Natl Acad Sci USA 84, 3623–3627

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  15. Katada T, Kusakabe K, Oinuma M, Ui M (1987) A novel mechanism for the inhibition of adenylate cyclase via inhibitory GTP-binding proteins. J Biol Chem 262, 11897–11900

    CAS  PubMed  Google Scholar 

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Supported by the grants from the Ministry of Education, Culture and Science of Japan and from the Calcium Signal Workshop on Cardiovascular Systems

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Kurachi, Y., Ito, H., Sugimoto, T. et al. Activation of atrial muscarinic K+ channels by low concentrations ofβγ subunits of rat brain G protein. Pflugers Arch. 413, 325–327 (1989). https://doi.org/10.1007/BF00583550

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  • DOI: https://doi.org/10.1007/BF00583550

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