Influence of the viscosity of iodixanol on medullary and cortical blood flow in the rat kidney: a potential cause of nephrotoxicity

The aim of the present study was to investigate the effects of four iodinat ed contrast media on cortical, inner medullary and outer medullary blood ho w in the rat kidney by using laser-Doppler flowmetry. The high-osmolar cont rast medium diatrizoate did not significantly modify medullary perfusion bu t moderately decreased the cortical blood flow when injected at a dose of 1 600 mg iodine kg(-1). Similar effects were obtained with the low-osmolar co ntrast media ioxaglate and iobitridol. In contrast, the new iso-osmolar con trast medium iodixanol induced a dose-dependent reduction of perfusion in a ll regions tested. This effect was accompanied by concomitant hypotension. The reduction of inner medullary and cortical blood flow induced by iodixan ol was partially alleviated by heating the solution prior to injection and subsequently reducing its viscosity. In the outer medulla, however, this pr ocedure did not improve blood flow. These results suggest that lowering the viscosity may palliate the harmful effects of iodixanol on the inner medul la and cortex, but may not protect the outer medulla from hypoxic injury. C opyright (C) 1999 John Wiley & Sons, Ltd.