Distribution and metabolism of ingested NO3- and NO2- in germfree and conventional-flora rats.
Germfree and conventional-flora Sprague-Dawley rats were fed sodium nitrate or sodium nitrite in their drinking water (1,000 microgram/ml), and various organs, tissues, and sections of the intestinal tract were assayed for nitrate (NO3-) and nitrite (NO2-) by a spectrophotometric method. When fed NO3-, germfree rats had chemically detectable levels of NO3- (only) in the stomach, small intestine, cecum, and colon. Conventional-flora rats fed NO3- had both NO3- and NO2- in the stomach, but only NO3- in the small intestine and colon. When fed NO2-, germfree rats had both NO3- and NO2- in the entire gastrointestinal tract. Conventional-flora rats fed NO2- had both ions in the stomach and small intestine, but only NO3- in the large intestine. Conventional-flora rats fed NO3- or NO2- had lower amounts of these ions in the gastrointestinal tract than comparably fed germfree rats. Control (non-NO3- or NO2--fed) germfree and conventional-flora rats had trace amounts of NO3- (only) in their stomachs and bladders. These results, in conjunction with various in vitro studies with intestinal contents, suggest that NO3- or NO2- reduction is a function of the normal bacterial flora, whereas NO2- oxidation is attributable to the mammalian host. In addition, the distribution of these ions after their ingestion appears more widespread in the body than previously thought.
D000818:Animals; D001419:Bacteria / Q000378:metabolism; D002432:Cecum / Q000032:analysis; D004064:Digestive System / Q000032:analysis / Q000382:microbiology*; D005856:Germ-Free Life; D066298:In Vitro Techniques; D007420:Intestine, Large / Q000032:analysis; D009566:Nitrates / Q000032:analysis / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D009928:Organ Specificity; D051381:Rats; D012977:Sodium Nitrite / Q000032:analysis / Q000378:metabolism
D009566:Nitrates; D009573:Nitrites; D012977:Sodium Nitrite