Enzyme changes in human small bowel mucosa during culture in vitro.

Human jejunal biopsy slices were maintained in culture for up to 48 hours. At 24 hours there was good morphological preservation but by 48 hours there was ultrastructural evidence of damage to the enterocytes. During culture the tissue had lost a certain amount of protein. At the same time the levels of three brush border enzymes (alkaline phosphatase, alpha-glucosidase, and leucyl-beta-naphthylamidase) and one lysosomal enzyme (N-acetyl-beta-glucosaminidase) showed a progressive decrease. Alkaline phosphatase, alpha-glucosidase, and N-acetyl-beta-glucosaminidase accumulated in the medium throughout the experimental period to give a medium:tissue distribution ratio of between 2 and 9. Leucyl-beta-naphthylamidase had a medium:tissue ratio of 140 after 48 hours of culture suggesting a selective secretion of this enzyme by the tissue.