A Preoperative Protein Free Diet Protects Against Renal Ischemia and Reperfusion Injury

Abstract

Background: Ischemia and reperfusion (I/R) injury is a serious and common complication of organ transplantation. Previously we showed that both two weeks of 30% dietary restriction and three days of preoperative fasting protects against renal I/R injury. In the present study, we investigated whether the protective effect was induced by a reduction of calories, or by absence of a specific food component. Materials and methods: Male C57BL/6 mice (n= 6/group) had ad libitum access to diets free of protein-, methionine-, tryptophan-,leucine, carbohydrate or fat before induction of renal I/R injury. Renal I/R injury was induced by clamping both kidneys during 37 minutes. After removing the clamp, I/R injury was assessed by serum urea levels and signs of animal discomfort. Mice fed ad libitum control diets and pair-fed (PF) controls for the deficient diets were used as control. Results: A 14 day preoperative protein-, methionine-, tryptophan- or leucine-free diet protected against renal I/R injury. PF controls revealed that mice on modified diets restricted their calorie intake by 30%. Since we previously showed that 30% dietary restriction for 14 days induces protection against I/R injury the effect of individual dietary components could not be separated from the effect of DR. Three days of 30% DR does not induce protection against I/R injury. Therefore we administered these diets during 3 preoperative days, and found that only the protein-free diet protected against renal I/R injury. Conclusion: A three day preoperative protein-deficient diet protects against renal I/R injury. These data show that the absence of protein is responsible for the protection induced by DR.