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 physi
ology 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 applicabi
lity to human intestinal protein metabolism and because of methodologic res
trictions, no studies on colon protein synthesis in situ are available in h
umans.
Methods
The authors used advanced mass spectrometry techniques (capillary gas chrom
atography and combustion isotope ratio mass spectrometry) to determine dire
ctly the incorporation rate of 1-[C-13]-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 infu
sion (0.16 mu mol/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 signifi
cantly lower, compatible with an increased colon proteolytic rate.
Conclusions
Elective abdominal surgery followed by an uncomplicated postoperative cours
e is associated with a stimulation of colon protein synthesis and possibly
also of protein degradation. The postoperative rate of colon protein synthe
sis is, compared with other tissues, among the highest measured thus far in
humans.