Effect of elective abdominal surgery on human colon protein synthesis in situ

OBJECTIVE: To determine the effect of elective abdominal surgery on the rate of human colon fractional protein synthesis in situ. SUMMARY BACKGROUND DATA: Efficient intestinal protein synthesis plays an important role in the physiology and pathophysiology of the intestinal tract, allowing preservation of gut integrity and thereby preventing bacterial or endotoxin translocation. Because of species differences, animal studies have only limited applicability to human intestinal protein metabolism, and because of methodologic restrictions, no studies on colon protein synthesis in situ are available in humans. METHODS: The authors used advanced mass spectrometry techniques (capillary gas chromatography and combustion isotope ratio mass spectrometry) to determine directly the incorporation rate of 1-[13C]-leucine into colon mucosal protein in control subjects and nonseptic postoperative patients. All subjects had a colostomy, which allowed easy access to the colon mucosa, and consecutive sampling from the same tissue was performed during continuous isotope infusion (0.16 micromol/kg per minute). RESULTS: Control subjects demonstrated a colon protein fractional synthetic rate of 0.74 +/- 0.09% per hour. In postsurgical patients, colon protein synthesis was significantly higher and the tissue free leucine enrichment was significantly lower, compatible with an increased colon proteolytic rate. CONCLUSIONS: Elective abdominal surgery followed by an uncomplicated postoperative course is associated with a stimulation of colon protein synthesis and possibly also of protein degradation. The postoperative rate of colon protein synthesis is, compared with other tissues, among the highest measured thus far in humans.