Effects of two dimeric iodinated contrast media on renal medullary blood perfusion and oxygenation in dogs

RATIONALE AND OBJECTIVES. To compare the effects of two iodinated contrast media, iodixanol and ioxaglate, on outer medullary blood flow (MBF) and oxygen tension (MPO2) in the dog kidney. METHODS. Iodixanol and ioxaglate were injected selectively into the renal artery (320 mgI/kg) of anesthetized Beagle dogs. MBF and MPO2 were measured with a laser-Doppler probe and an oxygen-sensing microelectrode implanted in the outer medulla. Urine samples were collected for viscosity and osmolality measurements. RESULTS. Both contrast media produced a moderate decrease in MBF and MPO2. The hypoperfusion and hypoxia lasted significantly longer with iodixanol than with ioxaglate. Theophylline, an adenosine receptor antagonist, partially prevented iodixanol-induced hypoxia. Urine viscosity was dramatically increased by iodixanol but not by ioxaglate. Urine osmolality did not differ significantly between groups. CONCLUSION. Iodixanol produced a more sustained medullary hypoxia than ioxaglate when injected selectively into the dog renal artery. This may lead to hypoxic cellular damage and subsequent impairment of kidney functions.