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 (MPO(2)) in the dog kidney.

Methods: Iodixanol and ioxaglate were injected selectively into the renal artery (320 mgI/kg) of anesthetized Beagle dogs. MBF and MPO(2) 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 MPO(2). 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.