NEW TECHNIQUE TO MEASURE MUCOSAL METABOLISM AND ITS USE TO MAP SUBSTRATE UTILIZATION IN THE HEALTHY-HUMAN LARGE-BOWEL

A new method of assessing substrate utilization in gastrointestinal mu cosal specimens is described. Small human endoscopic biopsy specimens with wet weights ranging between 1.4 and 12.2 mg were used to quantify the oxidation of three metabolic substrates, glucose, glutamine and b utyrate, through to carbon dioxide over a 2-h period. The technique pr oved to be reproducible and capable of distinguishing variations in mu cosal metabolism between individuals (P < 0.0001 for each substrate). Results were similar to those obtained previously using human and rat colonocytes. To characterize the metabolism of the healthy large bowel , specimens were obtained from five regions in 15 patients who had a n ormal colonoscopic examination. The results show that butyrate is the preferred fuel source of large bowel mucosa, followed by glutamine, th en glucose (P < 0.01). There was no significant regional variation in utilization of the three substrates between the five regions; with res pect to glutamine, this is contrary to previous findings.