Cyanide sensitive and insensitive bioenergetics in a clonal neuroblastoma x glioma hybrid cell line

The primary mechanism of cyanide (CN) intoxication is the inhibition of metabolism in the central nervous system. We determined the effects of CN on several biochemical processes in neuroblastoma x glioma hybrid NG108-15 cells, which possess numerous neuronal properties. These cells were not sensitive to a high concentration (1 mM) of NaCN, but became sensitive in the presence of the anaerobic glycolysis inhibitors sodium iodoacetate (IA) and 2-deoxyglucose (2-DG): cellular metabolic processes (e.g., DNA, RNA and protein synthesis) decreased, to about 40% of control due to treatment with 0.5 mM NaCN+0.05 mM IA and 0.1 mM NaCN+20 mM 2-DG. ATP in cells exposed to 0.01 or 0.1 mM NaCN+20 mM 2-DG was reduced 75% and 100%, respectively within one min. Pretreatment of cells with the CN antidote cobalt (II) chloride (CoCl₂) (0.06–0.18 mM) for 5 min prevented the depression of both [³H]leucine incorporation and ATP synthesis due to 1 mM NaCN+20 mM 2-DG in a concentration-dependent manner. A proposed CN antidote alpha-ketoglutaric acid (disodium salt) also prevented the depression of cellular metabolism due to NaCN plus 2-DG. These results indicate that blocking anaerobic glycolysis makes NG108-15 cells sensitive to a low concentration of CN. Thus NG108-15 cells should be useful to study the mechanisms of neurotoxicity of CN and to test antidotes.