Calcium signaling in neuronal cells exposed to the munitions compound Cyclotrimethylenetrinitramine (RDX).
Cyclotrimethylenetrinitramine (RDX) has been used extensively as an explosive in military munitions. Mechanisms for seizure production, seen in past animal studies, have not been described. Increased calcium levels contribute to excitotoxicity, so in this study neuroblastoma cells are loaded with calcium-indicating dye before application of 1.5 microM to 7.5 mM RDX, with fluorescence recorded for 30 cycles of 11 seconds each. The lowest concentration of RDX increases calcium fluorescence significantly above baseline for cycles 2 to 8; millimolar concentrations increase calcium fluorescence significantly above baseline for cycles 2 to 30. Increases in calcium, like those of 200 nM carbachol, are prevented with 10 mM of calcium chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N,N tetra-acetic acid (EGTA, tetrasodium salt). Calcium channel blocker verapamil (20 microM), Ca(2+)-ATPase inhibitor thapsigargin (5 microM), and general membrane stabilizer lidocaine (10 mM) partially attenuate carbachol- and RDX-induced increases in calcium, suggesting that RDX transiently increases intracellular calcium by multiple mechanisms.
Ehrich
Marion
M
Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia 24061, USA. marion@vt.edu
Wu
Xiaohua
X
Werre
Stephen R
SR
Major
Michael A
MA
McCain
Wilfred C
WC
Reddy
Gunda
G
D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects*; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D016895:Culture Media, Serum-Free; D004533:Egtazic Acid / Q000494:pharmacology; D053834:Explosive Agents / Q000633:toxicity*; D006801:Humans; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D014227:Triazines / Q000633:toxicity*
D002121:Calcium Channel Blockers; D002614:Chelating Agents; D016895:Culture Media, Serum-Free; D053834:Explosive Agents; D014227:Triazines; D004533:Egtazic Acid; D002118:Calcium; C009160:cyclonite