Role of Ca^<2+> Mobilization in Muscarinic Receptor-Mediated Membrane Depolarization in Guinea Pig Ileal Smooth Muscle Cells

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Author(s)

    • Unno Toshihiro UNNO Toshihiro
    • Laboratory of Pharmacology, Department of Veterinary Medicine, Faculty of Agriculture, United Graduate School, Gifu University
    • Inaba Tadafumi INABA Tadafumi
    • Laboratory of Pharmacology, Department of Veterinary Medicine, Faculty of Agriculture, United Graduate School, Gifu University
    • TAKEWAKI Tadashi
    • Department of Pathogenetic Veterinary Science, United Graduate School, Gifu University
    • KOMORI Seiichi
    • Laboratory of Pharmacology, Department of Veterinary Medicine, Faculty of Agriculture, United Graduate School, Gifu University

Abstract

In single smooth muscle cells dispersed from guinea pig ileum, the muscarinic agonist carbachol (CCh) at 2μM produced an oscillatory or sustained type of depolarization and at 100μM, the latter type depolarization. Depletion of internal Ca<SUP>2+</SUP> stores blocked the oscillatory response, but not the sustained responses to 2μM and 100μM CCh, although their decay after reaching the peak became faster. Blocking voltage-dependent Ca<SUP>2+</SUP> channels (VDCCs) blocked both types of response to 2μM CCh, but only slowed the initial rising phase of 100μM CCh responses. Combination of Ca<SUP>2+</SUP> store depletion and VDCC blockade abolished the responses to 2μM CCh again and decreased those to 100μM CCh in peak amplitude and persistency. Combination of Ca<SUP>2+</SUP> store depletion with removal of extracellular Ca<SUP>2+</SUP> markedly reduced or abolished the 100μM CCh responses. The results suggest that muscarinic depolarization of the ileal cells requires Ca<SUP>2+</SUP> mobilization for its generation and persistence; at weak muscarinic stimulation, both Ca<SUP>2+</SUP> entry via VDCCs and Ca<SUP>2+</SUP> release from internal stores may contribute to the Ca<SUP>2+</SUP> mobilization; and under strong muscarinic stimulation, Ca<SUP>2+</SUP> entry pathways resistant to VDCC blockers may also contribute to it.

Journal

  • The Japanese Journal of Pharmacology

    The Japanese Journal of Pharmacology 84(4), 431-437, 2000-12-01

    The Japanese Pharmacological Society

References:  24

Cited by:  1

Codes

  • NII Article ID (NAID)
    10008186762
  • NII NACSIS-CAT ID (NCID)
    AA00691188
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    00215198
  • NDL Article ID
    5612092
  • 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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