title: Radiation-induced generation of chlorine derivatives in N2O-saturated phosphate buffered saline: toxic effects on Escherichia coli cells.
abstract: The radiolysis of aqueous chloride solutions has been investigated using pulse and steady-state methods. We have found a correlation between the yields of Cl2- and HOCl formed in pulse-irradiated N2O-saturated solutions. The yields increased with the increasing concentrations of Cl- and phosphate. Phosphate enhanced the yield of Cl2- in neutral solutions because of a proton transfer from H2PO4- to HOCl- with a rate constant of (2.6 +/- 0.5) x 10(8) M-1s-1. HOCl could not be detected in pulse-irradiated He or air-saturated, phosphate-buffered saline (PBS) solutions or in gamma-irradiated N2O, He, or air-saturated PBS solutions. The results are discussed in light of previously suggested mechanisms for the formation and decay of Cl2-. Pulse-irradiated N2O-saturated PBS solutions have a lethal effect on Escherichia coli cells, which is proportional to the amount of HOCl in the solutions. Gamma-irradiation of cells in N2O-saturated PBS solution also raises the radiosensitivity of the cells, although HOCl does not accumulate in this system. The effects of the radiation-induced toxic products on E. coli cells are similar to the effects of NaOCl. The cell membrane is probably the site of physiological injury induced by the radiation products.
authors.affiliation: Department of Physical Chemistry, School of Medicine, Hebrew University of Jerusalem, Israel.
authors.forename: G
authors.initials: G
authors.lastname: Czapski
authors.forename: S
authors.initials: S
authors.lastname: Goldstein
authors.forename: N
authors.initials: N
authors.lastname: Andorn
authors.forename: J
authors.initials: J
authors.lastname: Aronovitch
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002021:Buffers; D002712:Chlorides / Q000737:chemistry / Q000494:pharmacology / Q000528:radiation effects*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000528:radiation effects; D016166:Free Radical Scavengers; D005609:Free Radicals; D005720:Gamma Rays; D009154:Mutation; D009609:Nitrous Oxide; D010710:Phosphates / Q000494:pharmacology*; D010756:Phosphoric Acids; D011522:Protons; D011675:Pulse Radiolysis; D011938:Rec A Recombinases / Q000235:genetics; D012965:Sodium Chloride; D012996:Solutions
chemical_list: D002021:Buffers; D002712:Chlorides; D016166:Free Radical Scavengers; D005609:Free Radicals; D010710:Phosphates; D010756:Phosphoric Acids; D011522:Protons; D012996:Solutions; D012965:Sodium Chloride; D000255:Adenosine Triphosphate; C030242:phosphoric acid; D011938:Rec A Recombinases; D009609:Nitrous Oxide