The effect of biliary diversion on mucosal enzyme activity and brush border glycoprotein degradation in rats with self-filling blind loops.

Abstract

Abstract. The significance of unconjugated bile salts in the development of mucosal lesions in the contaminated bowel syndrome was investigated by preparing jejunal self‐filling blind loops in rats in which pancreatic and biliary flow had been diverted to the mid ileum. Findings in these animals were compared with those in non‐operated controls, controls with the bile diversion procedure alone, and rats with self‐filling blind loops but unaltered biliary flow. Surface damage was monitored by determining relative glycoprotein degradation (3H/14C) ratios with the radioactive precursor D‐glucosamine, and measuring disaccharidase activities in mucosal homogenates and isolated brush border membranes. Data was analysed from the blind loop and segments above and below it, and compared with the corresponding upper, middle and lower segments of control rats. The blind loop, middle and upper intestinal segments of the rats with diverted bile flow contained no measurable bile salts. All rats with surgical procedures developed significant steatorrhoea. Fat excretion was greatest in the rats with the blind loop plus bile diversion. In rats with blind loops decreased conjugated:free bile salt ratios were found in all segments which contained bile, indicating excessive bacterial deconjugase activity. Disaccharidase activities were significantly reduced compared with control segments in homogenate and brush border fractions from self‐filling blind loops with and without bile salts. There was no difference between values in the two types of blind loop. Brush border glycoprotein degradation in the blind loops was significantly increased, to the same extent in both types of blind loop, but blind loop homogenate glycoprotein degradation was not altered indicating that degradation was specifically increased in the surface membrane. Blind loop disaccharidase activity in bile‐diverted animals was decreased out of proportion to changes in upper and lower segments and therefore was specifically related to the area of greatest bacterial overgrowth. These results indicate that factors other than bile salt deconjugation play a part in the pathogenesis of mucosal injury in the bacterially contaminated bowel.