Effects of Cyclophosphamide and Lactulose on the Release of Ammonia and Medium-Molecular-Weight Substances from the Intestine into Blood in Rats

The effects of lactulose on the release of ammonia and medium-molecular-weight substances from the intestine into the blood and on the severity of cyclophosphamide intoxication were studied in rats. The pH and urease-dependent component of ammonia-producing activity of the cecal chyme decreased over 6 h after lactulose administration, while ammonia content in the chyme increased. Cyclophosphamide caused an increase in ammonia and, less so, glutamine level in the portal blood and in the blood collected after decapitation; this drug stimulated release of methylene blue and endogenous substances of medium-molecular-weight to the portal blood. Lactulose was virtually inessential for these changes and for the neurological status, mortality, and medium life span of rats. Hence, lactulose did not prevent cyclophosphamideinduced leakage of ammonia and medium-molecular-weight substances from the gastrointestinal tract into blood and did not reduce the severity of intoxication.