Ischemic preconditioning of renal tissue: identification of early up-regulated genes

Given the important effects of ischemic preconditioning (IPC) in minimizing tissue damage induced by sustained ischemia in several tissues, this study evaluated the effect of IPC in preserving renal function and identified up-regulated genes after 30 min of preconditioning. IPC induced by 2, 3 and 4 min of ischemia, intercalated by 5 min of reperfusion, induced a measurable protection of renal function and morphology. The improved functional and histological parameters occurred in parallel with up-regulation of 39 genes, as evaluated by subtractive hybridization; for 13 of them we could show, by RNAse protection assay, a significant increase in mRNA levels. These genes code for chaperones/chaperonins and cytoskeleton proteins that could be involved in preservation of protein folding and cellular structures after sustained ischemia; proteins related to oxidative metabolism that might be relevant for cellular use of alternate sources of energy or for faster recovery of ATP levels in this condition, and proteins that are putative scavengers of oxidant products. Summarizing, ischemic preconditioning induced up-regulation of genes that code proteins whose functional roles suggest their involvement in the tolerance of the preconditioned tissue to sustained ischemia.