Calcium oscillations in single cultured Chinese hamster ovary cells stably transfected with a cloned human cholecystokinin (CCK)B receptor.
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.
Akagi
K
K
Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Japan.
Nagao
T
T
Urushidani
T
T
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism / Q000494:pharmacology; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D015220:Calcium Channels / Q000187:drug effects; D002999:Clone Cells / Q000502:physiology; D006224:Cricetinae; D005088:Exocrine Glands / Q000187:drug effects / Q000378:metabolism; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism; D005755:Gastrins / Q000494:pharmacology; D005765:Gastrointestinal Agents / Q000494:pharmacology; D006801:Humans; D010741:Phospholipases A / Q000502:physiology; D054467:Phospholipases A2; D011493:Protein Kinase C / Q000502:physiology; D011817:Rabbits; D043887:Receptor, Cholecystokinin B; D011949:Receptors, Cholecystokinin / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D012844:Sincalide / Q000494:pharmacology; D014162:Transfection
D015220:Calcium Channels; D005755:Gastrins; D005765:Gastrointestinal Agents; D043887:Receptor, Cholecystokinin B; D011949:Receptors, Cholecystokinin; D011994:Recombinant Proteins; D016718:Arachidonic Acid; D011493:Protein Kinase C; D010741:Phospholipases A; D054467:Phospholipases A2; D012844:Sincalide; D002118:Calcium