Expression of the Na+/Ca2+ Exchanger Ameliorates Ionomycin-Induced Cell Death

Abstract

PC12 cells were stably transfected with cDNA encoding the Na+/Ca2+ exchanger (NCX1.4). A robust Na+-dependent Ca2+ uptake confirmed the functional expression of the protein. When NCX1.4 expressing cells (NO) and vector transfected control cells (VC) were exposed to 0.5–20 μM ionomycin for 6 h, a dose-dependent increase in LDH release was observed. LDH release was significantly reduced in NO when compared with VC. When either VC and NO were treated with 3 μM ionomycin and 1.1 mM EGTA, the increase in LDH release was nearly abolished. However, when VC and NO were treated with ionomycin and then EGTA was added 2 min later, LDH release remained elevated. These data suggest ionomycin-induced cell death was Ca2+ dependent and expressing NCX1.4 may have ameliorated cell death by reducing elevated [Ca2+]I.