Expression of Two Different Cholecystokinin Receptors in Xenopus Oocytes Injected with mRNA from Rabbit Pancreas and Rat Hippocampus

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Electrophysiological responses to cholecystokinin (CCK) were studied in Xenopus oocyies injected with mRNA from rabbit pancreas or rat hippocampus. CCK-octapeptide(26-33) (sulfated form) (CCK-8) elicited inward currents in both groups. In oocyies injected with pancreatic mRNA, CCK-8-induced currents were composed of two components, fast and slow. However, in oocytes injected with hippocampal mRNA, fast currents disappeared. The potency ranking of the agonists and the antagonist indicated that the receptors expressed by pancreatic and hippocampal mRNA were CCK<SUB>A</SUB>-and CCK<SUB>B</SUB>-subtypes, respectively. Extracellular application of EGTA had little effect on the CCK<SUB>B</SUB>-mediated response, but attenuated the CCK<SUB>A</SUB>-mediated one. Intracellular injection of EGTA abolished the CCK<SUB>B</SUB>-mediated response, whereas small smooth currents remained in oocyies expressing the CCK<SUB>A</SUB>-receptor. The reversal potentials of the CCK<SUB>A</SUB>-and CCK<SUB>B</SUB>-receptor-mediated responses were consistent with that for Cl<SUP>-</SUP> currents. However, the reversal potential of the small smooth currents in EGTA-loaded oocytes expressing the CCK<SUB>A</SUB>-receptors was close to that for a non-selective cation channel. These results suggest that CCK-8 activates at least two different channels, a Ca<SUP>2+</SUP>-dependent Cl<SUP>-</SUP> channel and a non-selective cation channel in oocytes expressing the CCK<SUB>A</SUB>-receptor, while the CCK<SUB>B</SUB>-receptor elicits only a Ca<SUP>2+</SUP>-dependent Cl<SUP>-</SUP> channel.

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  • The Japanese journal of pharmacology

    The Japanese journal of pharmacology 72(1), 9-15, 1996-09-01

    The Japanese Pharmacological Society

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各種コード

  • NII論文ID(NAID)
    10008675507
  • NII書誌ID(NCID)
    AA00691188
  • 本文言語コード
    ENG
  • 資料種別
    ART
  • ISSN
    00215198
  • データ提供元
    CJP書誌  J-STAGE 
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