After surgical
trauma,
protein synthesis, as well as the concentration of free
glutamine in muscle, decreases.
Total parenteral nutrition (TPN) alone does not prevent the decrease of
glutamine in muscle, but TPN supplemented with
glutamine or its precursor,
alpha-ketoglutarate, maintains
amino acid concentration in muscle and preserves
protein synthesis. The aim of this study was to characterize a human
trauma model using patients undergoing
total hip replacement, and furthermore to investigate whether
glutamine or
alpha-ketoglutarate alone without TPN can prevent the postoperative decrease in muscle free
glutamine. Metabolically healthy patients undergoing
total hip replacement were randomized into three groups. The control group (n = 13) received
glucose 2 g/kg
body weight (BW) during surgery and the first 24 postoperative hours. The
glutamine group (n = 10) received
glucose 2 g/kg BW and
glutamine 0.28 g/kg BW, and the
alpha-ketoglutarate group (n = 10) received
glucose 2 g/kg BW and
alpha-ketoglutarate 0.28 g/kg BW. Muscle biopsies were performed before surgery and 24 hours postoperatively. Free
glutamine concentration in muscle decreased from 11.62 +/- 0.67 to 9.80 +/- 0.36 mmol/kg wet weight in the control group (P < .01), whereas it remained unchanged in both the
glutamine group and
alpha-ketoglutarate group.
Protein synthesis, as reflected by the concentration of total ribosomes, decreased significantly in the control group, but not in
glutamine and
alpha-ketoglutarate groups. Polyribosome concentration decreased significantly in both the control and
alpha-ketoglutarate groups.
Total hip replacement can be used as a reproducible
trauma model, with characteristic changes in the muscle
amino acid pattern and
protein synthesis 24 hours postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)