In vivo formation of nitrosocarbamates in the stomach of rats and guinea pigs
The N-nitrosocarbamates are potent mutagens and carcinogens and have been synthesized under acid conditions that prevail in the human stomach. However, it has never been documented that nitrosocarbamates are actually formed in vivo in the stomach of any mammalian species. Using /sup 14/C-labeled carbaryl and carbofuran, attempts were made to isolate the nitroso derivatives from the stomach contents of rats and guinea pigs treated orally with the carbamate and sodium nitrite. Only trace quantities of nitrocarbamate were recovered from the rat stomach, whereas 0.5 to 2.0% of the carbamate doses were isolated as the nitroso derivative from the contents of the guinea pig stomach. The rather low apparent yields resulted in part from the instability of the nitrosocarbamates and from absorption of the carbamate and/or nitrosocarbamate from the stomach. Higher rates of synthesis were indicated by incubating the carbamates with sodium nitrite in the presence of the stomach contents at 37/sup 0/C for 15 min. About 30% nitrosation occurred with the guinea pig and about 0.5% with the rat. The difference was attributed to the pH of the gastric contents. For the rat, the pH ranged from 3 to 5; gastric contents of the guinea pig had a pH between 1 and 2. Since the pH of the human stomach is also in the pH 1-2 range, it is likely that nitrosation of carbamates in humans would be very similar to that in the guinea pig. 21 references, 3 figures, 3 tables.
- Research Organization:
- Univ. of Kentucky, Lexington
- OSTI ID:
- 5946568
- Journal Information:
- J. Toxicol. Environ. Health; (United States), Vol. 14:2-3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBAMATES
CHEMICAL REACTIONS
METABOLISM
NITROSO COMPOUNDS
BIOSYNTHESIS
SODIUM NITRATES
CARBON 14 COMPOUNDS
CARCINOGENS
COMPARATIVE EVALUATIONS
EXPERIMENTAL DATA
GUINEA PIGS
MUTAGENS
PH VALUE
RATS
RESPONSE MODIFYING FACTORS
STOMACH
TRACER TECHNIQUES
ALKALI METAL COMPOUNDS
ANIMALS
BODY
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACID SALTS
DATA
DIGESTIVE SYSTEM
GASTROINTESTINAL TRACT
INFORMATION
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
NITRATES
NITROGEN COMPOUNDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
RODENTS
SODIUM COMPOUNDS
SYNTHESIS
VERTEBRATES
560305* - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)