An investigation of the endogenous formation of apparent total N-nitroso compounds in conventional microflora and germ-free rats

Food Chem Toxicol. 1988 Jul;26(7):595-600. doi: 10.1016/0278-6915(88)90230-x.


The endogenous formation of apparent total N-nitroso compounds (ATNC) has been investigated in germ-free (GF) and conventional (CV) microflora rats as a function of the drinking-water nitrate concentration. ATNC levels were below the 40 micrograms (N-NO)/kg detection limit in the blood, liver, kidney, spleen and small intestine of all CV and GF rats. For the CV rats ATNC were detected in concentrations of up to 370 micrograms (N-NO)/kg in the large intestine and up to 50 micrograms (N-NO)/kg in the stomach and there was a significant positive correlation between ATNC formation and the drinking-water nitrate level. Comparison of these results with those from GF rats showed that the ATNC in the stomach and large intestine of the CV animals were formed by microbial action, most probably involving bacterial nitrate-reductase activity.

MeSH terms

  • Animals
  • Food Analysis
  • Gastric Mucosa / metabolism
  • Germ-Free Life
  • Intestinal Mucosa / metabolism
  • Kidney / metabolism
  • Liver / metabolism
  • Nitrates / analysis
  • Nitroso Compounds / metabolism*
  • Rats
  • Rats, Inbred F344
  • Spleen / metabolism
  • Water Supply / analysis


  • Nitrates
  • Nitroso Compounds