THE ENDOGENOUS INSULIN-LIKE-GROWTH-FACTOR SYSTEM IN RADIOCONTRAST NEPHROPATHY

The response of insulin-like growth factor (IGF)I in acute renal failu re was evaluated in a model of radiocontrast nephropathy associated wi th selective necrosis of medullary thick ascending limbs. In brief, ra ts were administered radiocontrast medium or vehicle injections for co ntrols after combined inhibition of prostanoids and nitric oxide. Twen ty-four hours after the insult, tissue mRNAs for IGF-I, the IGF-I rece ptor, and IGF-binding proteins (IGFBP) 1 and 3 were assayed in cortex, medulla, and liver by solution hybridization-RNase protection assay, and IGFBPs were measured in serum and tissue by Western ligand blottin g. Cortical IGF-I increased, whereas medullary IGF-I mRNA decreased. R enal IGFBPs decreased, whereas IGFBP-1 mRNA increased. The IGF system in the liver was unchanged. We conclude that general changes in renal IGFBPs in this experimental model of acute renal failure might increas e the level of cortical IGF-I in a way that could modulate medullary r ecovery.