Inhibition of Ca^<2+> Entry Caused by Depolarization in Acetylcholine-Stimulated Antral Mucous Cells of Guinea Pig : G Protein Regulation of Ca^<2+> Permeable Channels

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Author(s)

Abstract

The effects of depolarizing conditions resulting from increasing extracellular K<sup>+</sup> concentration or nystatin treatment on intracellular Ca<sup>2+</sup> concentration ([Ca<sup>2+</sup>]<sub>i</sub>) were studied in guinea pig antral mucous cells following acetylcholine (ACh) stimulation. ACh stimulation evoked a biphasic increase in [Ca<sup>2+</sup>]<sub>i</sub>, that is, an initial transient increase followed by a plateau. Depolarizing conditions reduced the [Ca<sup>2+</sup>]<sub>i</sub> in the plateau phase during ACh stimulation. However, pertussis toxin (PTX, a G protein inhibitor) treatment caused [Ca<sup>2+</sup>]<sub>i</sub> in the ACh-evoked plateau phase to increase under depolarizing conditions, while it had no effect on [Ca<sup>2+</sup>]<sub>i</sub> under hyperpolarized conditions. Based on these observations, Ca<sup>2+</sup> permeable channels are regulated by a G protein which is activated by depolarized conditions and inhibited by hyperpolarized conditions and PTX; activation of the G protein (depolarization) causes Ca<sup>2+</sup> permeable channels to inhibit, and in turn, inhibition of the G protein (hyperpolarization) causes them to activate.<br>

Journal

  • The Japanese Journal of Physiology

    The Japanese Journal of Physiology 49(6), 545-550, 1999-12-01

    THE PHYSIOLOGICAL SOCIETY OF JAPAN

References:  14

Cited by:  2

Codes

  • NII Article ID (NAID)
    10008308372
  • NII NACSIS-CAT ID (NCID)
    AA00691224
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    0021521X
  • NDL Article ID
    4979622
  • NDL Source Classification
    ZS8(科学技術--医学--解剖学・生理学・生化学)
  • NDL Call No.
    Z53-D40
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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