Mobilization of Intracellular Ca^<2+> by Thromboxane A_2 Does Not Affect Ca^<2+>-Activated K^+ Channels in Rat Colonic Crypt Cells

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Author(s)

    • Sakai Hideki SAKAI Hideki
    • Department of Pharmaceutical Physiology, Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University
    • TAKEGUCHI Noriaki
    • Department of Pharmaceutical Physiology, Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University

Abstract

The effects of 9,11-epithio-11,12-methano-thromboxane A<sub>2</sub> (STA<sub>2</sub>), a stable thromboxane A<sub>2</sub> analogue, and carbachol on colonic Ca<sup>2+</sup>-activated K<sup>+</sup> channels were studied. In indo-1-loaded single cells in isolated rat colonic crypts, both STA<sub>2</sub> (0.1 μm) and carbachol (10 μm) transiently increased intracellular free Ca<sup>2+</sup> concentration ([Ca<sup>2+</sup>]<sub>i</sub>) by 136 and 155 nm, respectively. In whole-cell current-clamp experiments of the colonic crypt cells with Cl<sup>−</sup>-free solutions, carbachol (10 μm) hyperpolarized the cell by 19.7 mV, while STA<sub>2</sub> (0.1 μm) did not affect the membrane potential. In the isolated colonic mucosa that was permeabilized mucosally by a monovalent ionophore nystatin in the presence of a serosally directed K<sup>+</sup> gradient, carbachol (10 μm) transiently elicited K<sup>+</sup> current, but STA<sub>2</sub> (0.1 μm) did not. These results indicate that STA<sub>2 </sub>elevates [Ca<sup>2+</sup>]<sub>i</sub> in rat colonic crypt cells but does not activate basolateral Ca<sup>2+</sup>-activated K<sup>+</sup> channels.<br>

Journal

  • The Japanese Journal of Physiology

    The Japanese Journal of Physiology 50(3), 389-393, 2000-06

    THE PHYSIOLOGICAL SOCIETY OF JAPAN

References:  14

Codes

  • NII Article ID (NAID)
    10008291700
  • NII NACSIS-CAT ID (NCID)
    AA00691224
  • Text Lang
    ENG
  • Article Type
    SHO
  • ISSN
    0021521X
  • NDL Article ID
    5525816
  • 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  NDL  J-STAGE 
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