title: Ca2+ store-independent augmentation of [Ca2+]i responses to G-protein coupled receptor activation in recombinantly TRPC5-expressed rat pheochromocytoma (PC12) cells.
abstract: Mammalian homologues of the Drosophila canonical transient receptor potential (trp) protein (TRPC) have been implicated to function as receptor-operated Ca(2+) channels (ROCs) or store-operated Ca(2+) channels (SOCs). To determine the role of TRPC5 protein in neural cells, TRPC5 was recombinantly expressed in rat pheochromocytoma cells (PC12) and changes in intracellular Ca(2+) concentration ([Ca(2+)](i)) and Na(+) concentration ([Na(+)](i)) were analyzed. TRPC1 and TRPC3 mRNAs were endogenously expressed in PC12 cells. In TRPC5-expressed cells (TRPC5-cells), the resting [Ca(2+)](i) and [Na(+)](i) were significantly higher than those in control cells. The [Ca(2+)](i) increases induced by bradykinin and uridine 5'-triphosphate were significantly larger in TRPC5-cells. TRPC5 expression did not change in store-operated Ca(2+) entry elicited by thapsigarigin. TRPC5-cells showed larger inward current and increase of [Na(+)](i) in response to BK than control cells. These results suggest that TRPC5 channels expressed in PC12 cells function as ROCs activated by G-protein/phospholipase C coupled receptors, but not as SOCs.
authors.affiliation: Laboratory of Pharmacology, Department of Biomedical Science, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan. tihta@vetmed.hokudai.ac.jp
authors.forename: Toshio
authors.initials: T
authors.lastname: Ohta
authors.forename: Masataka
authors.initials: M
authors.lastname: Morishita
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Mori
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ito
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D016716:PC12 Cells; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000187:drug effects / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D014544:Uridine Triphosphate / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins; D012964:Sodium; D001920:Bradykinin; D002118:Calcium; D014544:Uridine Triphosphate