Mucosal enzyme activities, peptide hormone concentrations and hormone secretory granule properties in functioning...

Crosby capsule biopsies were obtained from functioning jejunum in 6 patients between 7 and 15 months after jejuno-ileal for morbid obesity and compared with 6 normal control biopsies. Brush border and other mucosal enzyme activities and seven regulatory peptide concentrations were measured in each biopsy. Analytical subcellular fractionation by sucrose density gradient centrifugation was used to investigate brush border and peptide secretory granule properties. Specific activities of all the brush border enzymes assayed in the bypass patients were similar to the normal controls and subcellular fractionation studies showed no change in brush border properties. Similarly, properties of other mucosal organelles and their associated enzyme activities were unchanged in the bypass patients. The mucosal regulatory peptide concentrations in the bypass patients showed no significant difference from the normal controls and no changes were detected in peptide storage granule properties. These studies therefore support the concept that the adaptive changes occurring after jejuno-ileal bypass are due to changes in cell numbers or other parameters of function rather than changes in the specific activities of the brush border enzymes themselves. They also show that the marked abnormalities of plasma hormone release after bypass surgery are not in themselves due to alterations in mucosal hormone concentrations, or of the secretory granule properties.