Figure 3: Viscosity of urine samples, urine flow rate, and glomerular filtration rate (GFR; measured by creatinine clearance) in rats before (control) and following contrast media administration (six 10 min sampling periods). Iopromide 370 mg I/per mL or iodixanol 320  mg I/mL was injected into the thoracic aorta as a bolus of 1.5 mL. Rats had access to drinking water prior to the experiment but were not hydrated by infusions. Data are mean ± SEM. * iopromide versus iodixanol. In all sample periods after contrast media injection, urine viscosities and urine flow rates were significantly higher than in the respective control sample. In rats receiving iodixanol, GFR was significantly lower than control GFR 10 to 40 min after iodixanol injection, whereas GFR remained unchanged in rats receiving iopromide. Note that GFR values for the first period following contrast media injection are not depicted, as high creatinine clearance values obtained for this period do not represent actual increases in GFR but rely on the dead-space effect. Redrawn from data in [39].