Background: Ischemia and reperfusion (I/R) injury is a serious and common complication after liver surgery and transplantation. We previously showed that three days of preoperative fasting protects against hepatic I/R injury. The protective effect was induced by the absence of protein, since a protein-free diet induced similar protection. To investigate whether total protein or single essential amino acids are responsible, we investigated the effects of a three-day preoperative amino acid free diet on hepatic I/R injury in mice.

Materials and methods: Male C57BL/6 mice were randomized into four groups (n=6/group). Three days before the induction of hepatic I/R injury they received either a control diet, a leucin-free, methionine-free or tryptophan-free diet. Bodyweight was recorded during the dietary intervention and after surgery. Hepatic I/R injury was induced by clamping 70% of the liver for 75 minutes. Serum ALAT and LDH levels and the percentage of necrosis in liver tissue were used to assess damage.

Results: Control diet fed mice gained 3% in weight. A leucin-free diet led to a reduction in bodyweight of 6.2%, tryptophan-free of 8.4% and methionine-free 9.5%. Postoperatively the control mice lost 10% of their body weight, while the mice on the deficient diets lost 0.5% on the first postoperative day. Six hours after reperfusion ALAT and LDH levels were significant lower in the leucin-free and tryptophan-free groups compared to the controls (P<0.05), and 24 hours after reperfusion liver enzymes were lower in the leucin-free, methionine-free and tryptophan-free groups (P<0.01). Liver tissue 24 hours after reperfusion showed significantly less necrosis in the methionine-free group (33.3%±sem6.2%) compared with the control group (77.5%±sem10.8%) (P<0.05). The leucine-free (34.4%±sem14.8%) and tryptophan-free (45.8%) diets showed a reduction that did not reach statistical significance.

Conclusion: A preoperative amino acid free diet limits the damage caused by hepatic I/R injury similar to fasting and a protein-free diet. Compared to fasting an amino acid free diet reduce weight loss. Therefore an amino acid free diet is a promising strategy to apply in the clinical setting.

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