PROTEIN-RESTRICTED DIET PRIOR TO RENAL INSULT IMPROVES THE RECOVERY OF RENAL-FUNCTION FOLLOWING ISCHEMIA

The effects of a protein-restricted diet on renal recovery following r enal ischemia were studied. The renal function was assessed by measuri ng the inulin clearance (C(IN)), the p-aminohippurate clearance (C(PAH )), and the percent fractional sodium excretion (%FE(Na)) 24 h after 4 5 min renal ischemia. In rats fed with a regular diet (containing 19.6 % protein), C(IN) was 10.0 +/- 2.2 muL/min/100 g body weight (BW), C(P AH) 0.08 +/- 0.02 mL/min/100 g BW, and %FE(Na) 14.8 +/- 2.0, 24 h afte r renal ischemia. In contrast, feeding rats with a no-protein diet (0% protein) for 1 week prior to the ischemic insult significantly improv ed renal recovery (C(IN) 48.0 +/- 9.3 muL/min/100 g BW, C(PAH) 0.16 +/ - 0.04 mL/min/100 g BW, and %FE(Na) 2.43 +/- 0.58). Feeding rats with a no-protein diet for 3 weeks prior to ischemic insult further improve d the renal recovery (C(IN) 113 +/- 30 muL/min/100 g BW, C(PAH) 0.47 /- 0.17 mL/min/100 g BW, and %FE(Na) 1.55 +/- 0.29). When rats fed wit h a regular diet were exposed to 45 min of ischemia, the survival rate on day 7 was 16.7%. In rats fed with the no-protein diet for 1 week a nd for 3 weeks, the 7-day survival rate was 100% in each case. The sur vival rate of rats fed for 3 days instead of 7 days with the no-protei n diet was 87.5%. When a no-protein feeding was shortened to 1 day, no beneficial effects were observed and survival rate was 14.3%. When th e ischemia time was prolonged to 60 min and 75 min, the 7-day survival rate with the regular diet was 0%, while the rates for the no-protein diet for 1 week were still 100%. Even after 90 min of ischemia, the 7 -day survival rate for rats with the no-protein diet was 60%. These re sults clearly demonstrate the beneficial effects of protein-restricted diet against postischemic acute renal failure.