title: Ionic dependence of sulphur mustard cytotoxicity.
abstract: The effect of ionic environment on sulphur mustard (bis 2-chloroethyl sulphide; HD) toxicity was examined in CHO-K1 cells. Cultures were treated with HD in different ionic environments at constant osmolar conditions (320 mOsM, pH 7.4). The cultures were refed with fresh culture medium 1h after HD exposure, and viability was assessed. Little toxicity was apparent when HD exposures were carried out in ion-free sucrose buffer compared to LC(50) values of approximately 100-150 microM when the cultures were treated with HD in culture medium. Addition of NaCl to the buffer increased HD toxicity in a salt concentration-dependent manner to values similar to those obtained in culture medium. HD toxicity was dependent on both cationic and anionic species with anionic environment playing a much larger role in determining toxicity. Substitution of NaI for NaCl in the treatment buffers increased HD toxicity by over 1000%. The activity of the sodium hydrogen exchanger (NHE) in recovering from cytosolic acidification in salt-free and in different chloride salts did not correlate with the HD-induced toxicity in these buffers. However, the inhibition by HD of intracellular pH regulation correlated with its toxicity in NaCl, NaI and sucrose buffers. Analytical chemical studies and the toxicity of the iodine mustard derivative ruled out the role of chemical reactions yielding differentially toxic species as being responsible for the differences in HD toxicity observed. This work demonstrates that the early events that HD sets into motion to cause toxicity are dependent on ionic environment, possibly due to intracellular pH deregulation.
authors.affiliation: Casualty Management Section, Defence Research & Development Canada-Suffield, Box 4000, Medicine Hat, Alberta T1A8K6, Canada. Thomas.Sawyer@drdc-rddc.gc.ca
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Sawyer
authors.forename: Peggy
authors.initials: P
authors.lastname: Nelson
authors.forename: Stephen
authors.initials: S
authors.lastname: Bjarnason
authors.forename: Cory
authors.initials: C
authors.lastname: Vair
authors.forename: Yimin
authors.initials: Y
authors.lastname: Shei
authors.forename: Catherine
authors.initials: C
authors.lastname: Tenn
authors.forename: Pierre
authors.initials: P
authors.lastname: Lecavalier
authors.forename: Andrew
authors.initials: A
authors.lastname: Burczyk
mesh_terms: D000643:Ammonium Chloride / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D002021:Buffers; D016466:CHO Cells; D053148:Caspase 3 / Q000378:metabolism; D018929:Cell Culture Techniques; D002470:Cell Survival / Q000187:drug effects; D002619:Chemical Warfare Agents / Q000633:toxicity*; D006224:Cricetinae; D003412:Cricetulus; D003470:Culture Media / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000737:chemistry; D009151:Mustard Gas / Q000633:toxicity*; D012492:Salts / Q000737:chemistry / Q000494:pharmacology*; D012965:Sodium Chloride / Q000737:chemistry / Q000494:pharmacology; D012974:Sodium Iodide / Q000737:chemistry / Q000494:pharmacology; D013395:Sucrose
chemical_list: D002021:Buffers; D002619:Chemical Warfare Agents; D003470:Culture Media; D012492:Salts; D000643:Ammonium Chloride; D012965:Sodium Chloride; D013395:Sucrose; D053148:Caspase 3; D012974:Sodium Iodide; D009151:Mustard Gas