Iodine concentrations in the rat kidney measured by X-ray microanalysis. Comparison of concentrations and viscosities in the proximal tubules and renal pelvis after intravenous injections of contrast media.

Purpose: To measure the iodine concentrations in the proximal tubules and renal pelvis after i.v. injections of contrast media (CM) at 1600 mg I/kg b.w., using a micropuncture technique and X-ray microanalysis.

Material And Methods: The correlation between the viscosity of each CM and its iodine concentration was evaluated and the viscosity of the fluid in the proximal tubule and renal pelvis was estimated in rats.

Results: After iotrolan injection, the iodine concentration in the proximal tubular fluid had increased to values about three times higher than those reached with diatrizoate, iohexol and ioxaglate. Similarly, iotrolan tended to produce a higher iodine concentration in the renal pelvis than did the other CM. The urine viscosity in the renal pelvis was much higher after the iotrolan injection than after the other CM injections.

Conclusion: High urine viscosity after iotrolan injection can at least partly explain our previous findings of a prolonged increase in tubular hydrostatic pressure and a prolonged decrease in the single nephron glomerular filtration rate after administration of this CM.