title: Protective efficacy of combined administration of lipopolysaccharide of E. coli and chemical radioprotectors under conditions of prolonged irradiation.
abstract: We investigated the protective effectiveness of the lipopolysaccharide of E. coli (LPS) in a combination with a mixture of chemical radioprotectors in female mice of the strain H at various radiation dose rates. LPS in a dose of 0.08 mg per kg of body mass was administered 1, 3, or 24 hours prior to irradiation, the radioprotective mixture (cystamine 90 mg X kg-1 + 5-methoxytryptamine 15 mg X kg-1) was administered 10 minutes before irradiation. Dose rates of 612 mGy X min-1 (irradiation time 10 to 15 minutes), 38 mGy X min-1 (3 to 4 hours), and 8.2 mGy X min-1 (27 to 29 hours) were used. The results showed that isolated administrations of LPS or of the radioprotective mixture increased the resistance of the mice against prolonged irradiation; the combined administration even enhanced the efficacy of the radioprotective action. However, this efficacy depended on the magnitude of the dose rate. At dose rates higher than 38 mGy X min-1 the effectiveness of the chemical protection prevailed, whereas at lower dose rates the biological and especially the combined protection became effective. We demonstrated a slight pyrogenic effect of LPS by measuring oxygen consumption and changes in some parameters of the hematopoiesis.
mesh_terms: D008735:5-Methoxytryptamine / Q000008:administration & dosage; D000818:Animals; D003538:Cystamine / Q000008:administration & dosage; D004359:Drug Therapy, Combination; D004926:Escherichia coli; D005260:Female; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D051379:Mice; D011833:Radiation Injuries, Experimental / Q000517:prevention & control*; D011837:Radiation-Protective Agents / Q000008:administration & dosage*
chemical_list: D008070:Lipopolysaccharides; D011837:Radiation-Protective Agents; D008735:5-Methoxytryptamine; D003538:Cystamine