title: Membrane depolarization combined with release of calcium from internal stores does not trigger secretion from PC 12 cells.
abstract: The mechanisms underlying catecholamine release from pheochromocytoma (PC 12) cells were examined. Whereas application of 1 microM bradykinin (BK) induced an increase in intracellular calcium ([Ca2+])i), either in medium containing 1.8 mM Ca2+ or in medium prepared without the addition of CaCl2 ("Ca(2+)-free medium"), norepinephrine ([3H]NE) release was induced only in Ca(2+)-containing medium. Similarly depolarization by 50 mM potassium induced [3H]NE release only in 1.8 mM calcium-containing medium. The combination of membrane depolarization (50 mM KCl) with increased [Ca2+]i secondary to BK application in "Ca(2+)-free medium" did not induce catecholamine secretion. It was concluded that Ca2+ entry through calcium channels at the plasma membrane is essential for the activation of catecholamine release. A rise in [Ca2+]i (4-5 times x basal) released from internal stores is not sufficient to trigger secretion from PC 12 cells, either by itself or in combination with membrane depolarization.
authors.affiliation: Department of Biological Chemistry, Hebrew University of Jerusalem.
authors.forename: U
authors.initials: U
authors.lastname: Ashery
authors.forename: C
authors.initials: C
authors.lastname: Weiss
authors.forename: D
authors.initials: D
authors.lastname: Sela
authors.forename: M E
authors.initials: ME
authors.lastname: Spira
authors.forename: D
authors.initials: D
authors.lastname: Atlas
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D004298:Dopamine / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D008564:Membrane Potentials; D009638:Norepinephrine / Q000378:metabolism*; D016716:PC12 Cells; D011188:Potassium / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; D011188:Potassium; D001920:Bradykinin; D002118:Calcium; D004298:Dopamine; D009638:Norepinephrine