Abstract
Rates of protein synthesis in vivo in normal and pathological tissues of the gastrointestinal tract, were measured using the 'flooding dose' technique with the stable isotope L-[1-13C] leucine. The rate of protein synthesis in normal colonic mucosa was 9.4 (1.2)% (mean (SEM)) per day but was significantly raised in benign and malignant colorectal tumour tissue, and in colonic mucosa from patients with inflammatory bowel disease (p less than 0.001). Furthermore, the rate of protein synthesis was significantly greater in benign colorectal tumour tissue, 36.7 (2.5)% per day, than that in either malignant tumour tissue, 21.7 (1.9)% per day, or in inflammatory bowel disease mucosa, 24.7 (2.5)% per day (means (SEM) p less than 0.001). Liver protein synthesis rates were also measured in separate groups of patients with benign disease of the gastrointestinal tract, in patients with colorectal carcinoma, and in patients with inflammatory bowel disease. The fractional rate of liver protein synthesis was 20.7 (1.9)% per day in patients with benign disease and 23.1 (1.6)% per day in patients with colorectal cancer. In patients with inflammatory bowel disease, however, liver protein synthesis was significantly increased to 35.4 (2.3)% per day (means (SEM) p less than 0.01).