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Ins(1,4,5)P 3 formation and fluctuating chloride current response induced by external ATP in Xenopus oocytes injected with embryonic guinea pig brain mRNA
Author(s) -
Fournier Franck,
Honoré Eric,
Collin Thibault,
Guilbault Pierre
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80845-a
Subject(s) - xenopus , extracellular , egta , adenosine , guinea pig , biophysics , intracellular , chemistry , adenosine triphosphate , biology , calcium , medicine , microbiology and biotechnology , endocrinology , biochemistry , gene
In voltage‐clamped Xenopus oocytes injected with embryonic guinea pig mRNA, effective concentrations of extracellular ATP elicited an inward fluctuating current. This current, carried by Cl‐ions, was mainly dependent upon liberation of Ca 2+ ions from stores as demonstrated by experiments using intracellular EGTA loading and TMB‐8 superfusion. Neomycin inhibited these fluctuating currents indicating that the transplanted purinoceptor is linked to phospholipase C activity and triggers Ins(1,4,5)P 3 formation. Ins(1,4,5)P 3 production evoked by external ATP was clearly demonstrated by directly measuring the water‐soluble Ins(1,4,5)P 3 level in injected oocytes. Finally, it is suggested that the ATP effect was mediated by a Ca 2+ release from Ins(1,4,5)P 3 sensitive pools since heparin blocked the ATP responsiveness. The acquired purinoceptor may be made apparent to a P 2 subtype since ATP and ADP were equipotent in eliciting Cl − current while AMP and Adenosine were ineffective in injected oocytes.