Protein synthesis in skeletal muscle in relation to nitrogen balance after abdominal surgery: the effect of total parenteral nutrition.

Protein synthesis in skeletal muscle was studied in patients after elective abdominal surgery, using the concentration and size distribution of ribosomes. The patients were given either an electrolyte solution or total parenteral nutrition postoperatively. The analyses were performed on muscle biopsy specimens taken prior to surgery and on days 1 and 3 following surgery. The percentage content of polyribosomes, total ribosome concentration and the polyribosome concentrations per milligram of tissue DNA were determined. Elective abdominal surgery caused a significant decrease (p less than 0.05) in the three variables. Total parenteral nutrition did not prevent the decrease. The negative nitrogen balance was significantly improved by total parenteral nutrition, but it did not reach equilibrium. The results show that total parenteral nutrition given postoperatively did not maintain protein synthesis activity in skeletal muscle. The improvement in nitrogen balance suggests that amino acids are utilized by tissues other than skeletal muscle.