title: Functional coupling of secretion and capacitative calcium entry in PC12 cells.
abstract: The caffeine-evoked effects on the intracellular Ca2+ concentration ([Ca2+]i) and on the release of dopamine by PC12 cells were investigated. Stimulation by caffeine resulted in a transient Ca2+ release which was followed by a sustained phase of Ca2+ entry through a non-voltage dependent pathway. Treatment with cyclopiazonic acid (CPA) or thapsigargin, inhibitors of the Ca2+ ATPase pump of the endoplasmic reticulum, resulted in only a sustained rise in [Ca2+]i in the presence of extracellular Ca2+. Pretreatment of cells with CPA or thapsigargin abolished the subsequent Ca2+ responses to caffeine. Caffeine also evoked the release of dopamine from the cells only in the presence of extracellular Ca2+, which was mimicked by CPA. These results suggest that store-dependent Ca2+ entry evoked by caffeine has an indispensable role in the secretory response in an excitable cell line, PC12 cells.
authors.affiliation: Division of Pharmacology, National Institute of Health Sciences, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Koizumi
authors.forename: K
authors.initials: K
authors.lastname: Inoue
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D002413:Cations, Divalent; D004298:Dopamine / Q000378:metabolism; D005089:Exocytosis / Q000502:physiology; D005110:Extracellular Space / Q000502:physiology; D007211:Indoles / Q000494:pharmacology; D007424:Intracellular Fluid / Q000502:physiology; D016716:PC12 Cells; D051381:Rats; D015398:Signal Transduction / Q000502:physiology*; D013806:Theophylline / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002413:Cations, Divalent; D007211:Indoles; D002110:Caffeine; D013806:Theophylline; D015032:Zinc; D002118:Calcium; D004298:Dopamine; C000543:cyclopiazonic acid