Male pigs (Strain Large white; INRA, Le Magneraud, Surgères, France) were prepared as previously described.23 Prolonged WI was induced by clamping the renal pedicle for 90 minutes with a vascular nontraumatic clamp. To simulate the planned period of WI and different nephron mass conditions, three experimental groups were studied: pigs with bilateral renal ischemia lasting 90 minutes (WI90, n = 7), pigs with unilateral WI and contralateral nephrectomy (50% of nephron mass reduction, 1/2N×90, n = 7), and pigs with unilateral WI without contralateral nephrectomy (WIuni90, n = 7). These two last groups were designed to assess the effect of nephron mass after WI.