['To assess the impact of a standard moderately severe surgical operation on the mucosal amino acid content of the duodenum and the colon.', 'Open study.', 'University hospital, Sweden.', 'Nine patients who were to undergo elective open cholecystectomy.', 'Endoscopically obtained biopsy specimens from the intestinal mucosa.', 'Changes in the content of free amino acids in the duodenum and colon at three days postoperatively.', 'The concentration of glutamine in the duodenum increased by 27% and that of glutamic acid by 34% after operation, whereas their content in colon remained unaltered. The concentration of branched chain amino acids increased by 26% in the duodenal mucosa after operation and by 24% in the colonic mucosa. The total concentration of amino acids (excluding taurine) increased by 9% in the duodenum, but remained unaltered in the colon.'] Do elective abdominal operations alter the free amino acid content of the human intestinal mucosa?