Ischemic preconditioning attenuates functional, metabolic, and morphologicinjury from ischemic acute renal failure in the rat

Ischemic preconditioning has been shown to ameliorate injury due to subsequ ent ischemia in several organs. However, relatively little is known about p reconditioning and the kidney. To address this rats were randomized to cont rol (C, N=14), 2 min of ischemic preconditioning (P2 N=10), 3 periods of 2 min of ischemia separated by 5 min periods of reflow (P2,3 N=7), or three 5 min periods of ischemia separated by 5 min of reflow (P5,3 N=6) prior to 4 5 min of bilateral renal ischemia followed by 24 hours of reperfusion. We o bserved a lower serum creatinine after 24 hours of reflow in P2, P2, 3 but not P5, 3 rats compared with C. Histology was examined in the C and P2, 3 g roups and demonstrated less ser,ere injury in the P2, 3 group, To gain insi ght into the mechanism by Which preconditioning ameliorated ischemic injury , we performed near IR spectroscopy and P-31 NMR spectroscopy. Based on nea r IR spectroscopy, the P2, 3 group had closer coupling of cytochrome aa3 re dox state With that of hemoglobin during reflow. In the P-31 NMR studies, t he changes in ATP and pHi were similar during ischemia, but the P2, 3 group recovered ATP and pHi faster than C. These data suggest that ischemic preconditioning may ameliorate ischemic re nal injury as assessed by functional, metabolic and morphological methods. The mechanism(s) by which this occurs requires additional study.