title: Role of Ca2+ in radiation-induced damage in murine splenocytes.
abstract: OBJECTIVE
  To address the links between calcium, peroxidation, cell damage and death and the response of the enzymes involved in free radical metabolism, in splenocytes of mice irradiated with gamma-rays.
  
  
  METHODS
  Splenocytes of Swiss albino mice were irradiated with various doses (0-7 Gy) of gamma-rays (60Co) at a dose-rate of 0.0575 Gy s(-1). Membrane peroxidation and fluidity were determined by the thiobarbituric acid-reactive substances (TBARS) method, and fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), respectively. Apoptosis was analysed by nucleosomal ladder formation and activity of NF-kappaB by electrophoretic mobility shift assay (EMSA). The specific activities of the antioxidant enzymes, lactate dehydrogenase (LDH), levels of nitric oxide (NO*) and glutathione were determined spectrophotometrically. Modulatory effects of Ca2+ were examined at 3 Gy using different concentrations (1, 3 and 5 mM) in the presence or absence of the ionophore A23187.
  
  
  RESULTS
  Irradiation of splenocytes resulted in enhanced peroxidative damage. membrane fluidity, apoptosis and DNA binding activity of NF-kappaB. The specific activities of LDH and antioxidant enzymes superoxide dismutase (SOD), DT-diaphorase (DTD), glutathione S-transferase (GST) and levels of glutathione (GSH) and NO* were increased with radiation dose up to 4Gy. Ca2+ augmented the radiation-induced responses. The presence of ionophore A23187 potentiated the modulatory effects of Ca2+.
  
  
  CONCLUSIONS
  These findings show that Ca2+ augments radiation damage and is more effective intracellularly. Ca2+, peroxidation, cellular damage and apoptosis are possibly interlinked through signals, as is evident from the increased activity of NF-kappaB and generation of NO*. The enhanced antioxidant status suggests an attempt made by the irradiated cells to maintain their normal functions.
authors.affiliation: Free Radical Biology laboratory, School of Iife Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
authors.forename: A
authors.initials: A
authors.lastname: Agrawal
authors.forename: S
authors.initials: S
authors.lastname: Shukla
authors.forename: R K
authors.initials: RK
authors.lastname: Kale
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology / Q000528:radiation effects; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004307:Dose-Response Relationship, Radiation; D004789:Enzyme Activation / Q000528:radiation effects; D005720:Gamma Rays; D015227:Lipid Peroxidation / Q000528:radiation effects*; D008297:Male; D008560:Membrane Fluidity / Q000528:radiation effects*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D011829:Radiation Dosage; D013154:Spleen / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*
chemical_list: D000975:Antioxidants; D016328:NF-kappa B; D009569:Nitric Oxide; D002118:Calcium