Dietary protein regimen prior to renal ischemia significantly affects the postischemic uremic response

Recently we reported that maintaining rats on restricted dietary protein regimens prior to renal ischemia will significantly improve postischemic survival rates. This effect required a week or more of maintenance on a restricted protein diet prior to the renal insult and appeared to be independent of the postischemic dietary protein regimen. The present study was designed to evaluate the role of systemic toxicity in this protection. Adult male Sprague-Dawley rats were pair-fed by weight on restricted or high isocaloric protein diets for 8-10 days prior to 45 min of renal ischemia induced by renal pedicle clamping. When placed on a normal dietary protein regimen immediately following ischemia, the rats preconditioned to restricted dietary protein exhibited significantly less acidosis, less hyperkalemia, lower blood urea nitrogen values, and improved survival rates compared with rats preconditioned on a high dietary protein regimen. In order to separate the possible effects of prior dietary protein regimen on acute tubular necrosis suffered during renal ischemia from its effects on the uremic response, bilateral nephrectomies were performed on rats preconditioned for 14 days to low, normal, and high dietary protein regimens. Although all of the rats were placed on the same dietary protein regimen immediately following bilateral nephrectomy, those that had previously been on a lower dietary protein regimen exhibited a significantly reduced uremic response and lived longer. These findings indicate that dietary protein regimen prior to renal ischemia is a risk factor which can have a significant lingering effect on the severity of postischemic systemic toxicity.