Abstract
The effects of various cathartics (magnesium sulfate, mannitol, dioctyl sodium sulfosuccinate (DSS), castor oil and pilocarpine) and deoxycholic acid (DCA) on the disposition of endogenous bile acids in the bile, portal blood and feces of rats were investigated. The biliary bile acids of free type increased significantly after the oral administration of cathartics except for DSS. The amounts of glyco- and tauro-conjugated bile acids showed different patterns after the oral administration of various cathartics. However, the proportion of DCA significantly increased in the case of diarrhea induced by cathartics, and the proportion of cholic acid (CA) conversely decreased compared with the control. Thus, it was suggested that unconjugated bile acids eliminated into the intestinal lumen and DCA formed from CA participate in the occurrence of diarrhea after oral administration of various cathartics. Moreover, the ratio of glycine- to taurine-conjugated bile acid of rat bile increased when diarrhea was induced by various cathartics. Thus result suggested that the reabsorption of tauro-conjugated bile acids is decreased, or that the reabsorption of glyco-conjugated bile is increased in diarrhea.On the other hand, DCA caused diarrhea in rats. The occurrence of diarrhea was concentrated within 20 to 24 h after the oral administration of DCA. Since biliary unconjugated and glyco-conjugated bile acids were increased at 24 h after DCA treatment, whereas glyco-conjugated bile acids were decreased in the portal blood, it is conceivable that deconjugation is accelerated by changes in the activity of intestinal bacteria and in the liver after DCA treatment. Active transport of tauro-conjugated bile acids from the end of the ileum may have been impaired, because the absorption of tauro-conjugated bile acids was inhibited from 1 h after the administration of DCA.
