Possible Role of Potassium Channels in Mu-receptor-Mediated Inhibition and Muscarinic Autoinhibition in Acetylcholine Release From Myenteric Plexus of Guinea Pig Ileum

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Author(s)

    • Saitoh Noriko SAITOH Noriko
    • Department of Veterinary Pharmacology, College of Agriculture, Research Institute for Advanced Science and Technology, Osaka Prefecture University
    • TAKEUCHI Tadayoshi
    • Department of Veterinary Pharmacology, College of Agriculture, Research Institute for Advanced Science and Technology, Osaka Prefecture University
    • HATA Fumiaki
    • Department of Veterinary Pharmacology, College of Agriculture, Research Institute for Advanced Science and Technology, Osaka Prefecture University

Abstract

It is known that mu-agonists inhibit electrical field stimulation(EFS)-evoked ACh release from longitudinal muscle myenteric plexus(LMMP)preparation of guinea pig ileum when muscarinic autoinhibition does not fully work.In the present study, the possible role of K<SUP>+</SUP> channels in the mechanisms of mu-agonists-induced inhibition and autoinhibition of ACh release was studied.In the presence of atropine, which blocks the autoinhibition, non-selective K<SUP>+</SUP> channel blockers, tetraethylammonium(TEA)and 4-amino-pyridine(4-AP), reversed the inhibitory effect of mu-agonists, morphine and [D-Ala<SUP>2</SUP>, N-Me-Phe<SUP>4</SUP>, Gly<SUP>5</SUP>-ol]enkephalin, on EFS-evoked ACh release, but not that of kappa-agonist U-50, 488.Apamin, iberiotoxin or glibenclamide did not affect the inhibition of ACh release by morphine.On the other hand, in the absence of atropine(under the autoinhibition working condition), 4-AP increased EFS-evoked ACh release, but atropine did not further increase ACh release in the presence of 4-AP.In contrast, although TEA did not affect EFS-evoked ACh release, atropine increased ACh release in the presence of TEA.These results suggest that the inhibitory effects of mu-agonists and muscarinic autoinhibition on the ACh release are associated with activation of different types of K<SUP>+</SUP> channels in the guinea pig LMMP preparations:the former is associated with 4-AP- and TEA-sensitive K<SUP>+</SUP> channels and the latter is associated with 4-AP- but not TEA-sensitive K<SUP>+</SUP> channels.

Journal

  • The Japanese Journal of Pharmacology

    The Japanese Journal of Pharmacology 82(4), 343-349, 2000-04-01

    The Japanese Pharmacological Society

References:  36

Cited by:  1

Codes

  • NII Article ID (NAID)
    10008184003
  • NII NACSIS-CAT ID (NCID)
    AA00691188
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    00215198
  • NDL Article ID
    5362824
  • NDL Source Classification
    ZS51(科学技術--薬学)
  • NDL Call No.
    Z53-D199
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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