Effects of non-ionic monomeric and dimeric iodinated contrast media on renal and systemic haemodynamics in rats

Non-ionic dimeric contrast media (CM) are a :new class of CM which are iso- osmolar with plasma. The aim of this study was to investigate their effects on systemic and renal haemodynamics. The non-ionic dimeric CM iodixanol an d the non-ionic monomeric agent iobitridol (both at a dose of 1 600 mgI/kg) were compared in terms of their effects on systemic blood pressure (BP) an d renal blood how (RBF) in two strains of rats (Wistar and Sprague Dawley). Iodixanol significantly lowered BP in Wistar rats (- 33 +/- 9% of baseline , 10 min post-injection, P<0.001 vs, saline and iobitridol). Iobitridol had virtually no effect on BP. Iobitridol and iodixanol significantly decrease d RBF. This effect was more marked following injection of the dimer rather than the monomer (iodixanol: - 32 +/- 13%, iobitridol: - 20 +/- 4% of basel ine at 16 min, P < 0.05). For both agents, RBF was still decreased 50 min f ollowing injection (iodixanol: - 30 +/- 11% and iobitridol: - 20 +/- 5% of baseline), Iodixanol also decreased RBF in Sprague Dawley rats, while BP re mained unchanged. This suggests that changes in BP/RBF autoregulation do no t account fbr the renal haemodynamic effects of this agent. When measured 2 h following injection, the iodixanol-induced renal hypoperfusion was still detectable (- 29% vs. saline-treated rats), although not significant (P = 0.06). This effect was no longer observed 4 h following injection. Increasi ng the saline infusion rate (18 mL/h vs. 2 mL/h) during the experiment did not significantly decrease the effects of iodixanol on BP and RBF in Wistar rats. In spite of its iso-osmolality, iodixanol, a non-ionic dimeric CM, d epressed RBF and BP significantly more than iobitridol, a monomeric non-ion ic agent, in Wistar rats. This effect was long-lasting and was not alleviat ed by increasing the hydration rate. (C) 2000 Editions scientifiques et med icales Elsevier SAS.