The Relative Importance of the Small Intestine and the Liver in Phase II Metabolic Transformations and Elimination of p-Nitrophenol Administered in Different Doses in the Rat

Intestinal and hepatic function have been investigated in phase II metabolic reactions and elimination of p-nitrophenol (PNP) in the rat. A jejunal loop was cannulated and recirculated with isotonic solutions containing PNP in different concentrations (0, 20, 100, 500, 1000 µM). Samples were obtained from the perfusate at given intervals. To investigate the metabolic and excretory functions of the liver, the bile duct was cannulated, and the bile was collected. Metabolites of PNP were determined by validated HPLC (high pressure liquid chromatography) methods. The results demonstrated the relative importance of the small intestine and the liver in phase II metabolic transformations and elimination of PNP. There were significant differences between the luminal and biliary appearances of p-nitrophenol-glucuronide (PNP-G) and p-nitrophenol–sulfate (PNP-S). The PNP-G appeared in the intestinal lumen at the lower PNP concentrations (20 µM and 100 µM) at higher rate than in the bile. No significant difference was found between the intestinal and the biliary excretion of PNP-G when PNP was administered at a concentration of 500 µM. However, a reverse ratio of these parameters was observed at the administration of 1000 µM PNP. The results indicated that both the small intestine and the liver might play an important role in phase II metabolic reactions and elimination of PNP. However, the relative importance of the small intestine and the liver can be dependent on the dose of drugs.

Effects of Mesalazine on Morphological and Functional Changes in the Indomethacin-Induced Inflammatory Bowel Disease (Rat Model of Crohn's Disease)

Morphological and functional changes have been investigated in the rat model of Crohn's disease. The inflammatory bowel disease was induced by indomethacin (1 × 10 mg/kg s.c. for 3 days). Morphological alterations were evaluated by macroscopic scoring system and on the base of histological changes in the small intestine. Functional activities were studied by determination of the intestinal and hepatic elimination of p-Nitrophenol (PNP) and its metabolites (PNP-glucuronide: PNP-G and PNP-sulfate: PNP-S) during the luminal perfusion of PNP. It was found that the indomethacin induced severe macroscopic changes (hyperaemia, petechia, bleeding, erosions, ulcerations) and significant histological alterations in the small intestine of rats which were definitely inhibited by mesalazine (1000 mg/kg by gastric tube for 3 days). Disappearance of PNP from the luminal perfusion solution was diminished by indomethacin which was corrected by administration of mesalazine. Significant depression was found in the luminal appearance of PNP metabolites by giving of indomethacin and these alterations could not be compensated by mesalazine.Hepatic elimination of PNP (biliary excretion of PNP and its metabolites) was decreased definitely by indomethacin which was - at least partly - compensated by mesalazine.The findings of the present study suggest that the indomethacin-induced inflammation in the small intestine represents a useful rat model of Crohn's disease. Morphological and functional alterations caused by indomethacin can be compensated by mesalazine.

Effects of fructus psoraleae extract on the intestinal absorption kinetics of geniposide and geniposidic acid in rat

Cortex Eucommia has been used as a kidney-tonifying herbal medicine with a long history of compatibility with Fructus Psoraleae. Geniposide (GP) and geniposidic acid (GPA) are the two main chemical components in Cortex Eucommia. In the present study, the effects of Fructus Psoraleae extract (FPE) on intestinal absorption kinetics of GP and GPA in rat were investigated. Twenty four male Sprague-Dawley rats were randomly assigned into four groups which were treated with GP, GPA, GP mixed with FPE and GPA mixed with FPE, respectively, by in situ intestinal perfusion for 3 h. The samples of intestinal perfusion solutions were collected every 30 min, and analyzed by ultra high performance liquid chromatography (UPLC). The curves of time and residual quantities of GP and GPA (lnx) in the intestinal perfusion solution and the cumulative absorption rate were obtained. The results showed that FPE exhibited different effects on the intestinal absorption of GP and GPA in rat: it increased the intestinal absorption of GP (p<0.05), while demonstrated no significant effect on the absorption of GPA.