BIOSYNTHETIC HUMAN GROWTH-HORMONE PRESERVES BOTH MUSCLE PROTEIN-SYNTHESIS AND THE DECREASE IN MUSCLE-FREE GLUTAMINE, AND IMPROVES WHOLE-BODY NITROGEN ECONOMY AFTER OPERATION

As a reproducible human trauma model, patients (n = 17) undergoing elective cholecystectomy were studied for 3 postoperative days. They were randomly allocated to receive either recombinant human growth hormone (hGH; 0.3 U/kg/24 hours) or placebo together with total parenteral nutrition, including 0.2 gN/kg/24 hours and 135 kJ/kg/24 hours. Before operation and on the third postoperative day, percutaneous muscle biopsies were performed to determine the concentration and size distribution of ribosomes and the free amino acid concentrations. The significant postoperative decrease in the total ribosome concentration (15.3 +/- 6.4%) and the polyribosome concentration (20.9 +/- 6.5%) in the control group was impeded in the group receiving synthetic hGH. Muscle free glutamine decreased by 35.6 +/- 4.2% in the control group and to a lesser extent in the group that was given hGH after operation (p < 0.05). The protein content of skeletal muscle was unchanged. The cumulated nitrogen balance for the study period was negative in the control group (-7.09 +/- 0.71 gN), but was not different from zero in the hGH group (-2.32 +/- 1.66 gN). It is concluded that synthetic hGH administered after operation has beneficial effects on the whole-body nitrogen economy, as indicated by the unchanged capacity for protein synthesis in skeletal muscle, the preserved levels of muscle free glutamine, and improvement in the whole-body nitrogen balance. The effects of hGH on skeletal muscle protein and amino acid metabolism can explain the postoperative nitrogen-sparing effect attributed to hGH.