Open AccessCalcium Oscillations in Single Cultured Chinese Hamster Ovary Cells Stably Transfected with a Cloned Human Cholecystokinin (CCK)B Receptor.
Author(s) -
Kenzo Akagi,
Taku Nagao,
Tetsuro Urushidani
Publication year - 1997
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.75.33
Subject(s) - cholecystokinin , chinese hamster ovary cell , extracellular , arachidonic acid , cholecystokinin receptor , phospholipase a2 , phospholipase c , biology , receptor , protein kinase c , medicine , aristolochic acid , endocrinology , transfection , phospholipase , microbiology and biotechnology , chemistry , biochemistry , signal transduction , enzyme , genetics , gene
In Chinese hamster ovary cells stably expressing the cloned human cholecystokinin (CCK)B/ gastrin receptor, cholecystokinin octapeptide (CCK-8) evoked increases in [Ca2+]i monitored by digitized video imaging of fura-2 fluorescence ratios. At concentrations around 10 pM, CCK-8 elicited [Ca2+]i oscillations, which were blocked by elimination of extracellular Ca2+, by a phospholipase C inhibitor, U-73122, by a protein kinase C inhibitor, H7, as well as by phospholipase A2 (PLA2) inhibitors, ONO-RS-082 and aristolochic acid. At higher concentrations, CCK-8 induced a single biphasic [Ca2+]i rise consisting of a large peak followed by a lower sustained plateau, while the response turned into [Ca2+]i oscillation when the extracellular Ca2+ was eliminated or a PLA2 inhibitor was included. CCK-8 stimulated the release of arachidonic acid, and this was inhibited by aristolochic acid. Arachidonic acid caused an increase in [Ca2+]i which was dependent upon extracellular Ca2+. These results suggest that the activation of PLA2 might be involved, at least in part, in the Ca2+ influx that maintains the sustained plateau phase of [Ca2+]i as well as the [Ca2+]i oscillation when CCKB receptors are stimulated.