title: Evaluation of radiochemical protectors using urinary deoxycytidine levels.
abstract: It is customary to use the LD50 response as a criterion for the evaluation of chemical radioprotection. The increased urinary excretion of deoxycytidine (CdR) in irradiated rats has been shown to be a linear dose--response relationship up to 200 R, thus making it possible to consider such a response as a criterion for chemical radioprotection evaluation at sub-lethal irradiation levels. Rats were subjected to 200 R X-irradiation with various chemical protectors and without chemical protectors, urine was collected 24 hours after irradiation, and the CdR levels in the urine analysed. A dose-reduction factor (DRF) was determined for 24-hour urinary excretions of CdR for chemically protected and non-protected rats. The DRF values are within 6 per cent of those reported by other investigators using LD50 as the response criterion for serotonin, cysteine, MEA and PAPP but differ for WR-2721 and WR-2823. Agreement using WR-2721 and WR-2823 compounds is only obtained when the toxicity effect of the compound is taken into consideration.
mesh_terms: D000818:Animals; D003545:Cysteine / Q000627:therapeutic use; D003841:Deoxycytidine / Q000652:urine*; D004307:Dose-Response Relationship, Radiation; D005069:Evaluation Studies as Topic; D005260:Female; D008624:Mercaptoethylamines / Q000627:therapeutic use; D009946:Organothiophosphorus Compounds / Q000627:therapeutic use; D011427:Propiophenones / Q000627:therapeutic use; D011833:Radiation Injuries, Experimental / Q000517:prevention & control / Q000652:urine*; D011837:Radiation-Protective Agents / Q000627:therapeutic use*; D051381:Rats; D012701:Serotonin / Q000627:therapeutic use; D014965:X-Rays
chemical_list: D008624:Mercaptoethylamines; D009946:Organothiophosphorus Compounds; D011427:Propiophenones; D011837:Radiation-Protective Agents; D003841:Deoxycytidine; D012701:Serotonin; D003545:Cysteine