Nonionic contrast media iohexol and iomeprol decrease renal arterial tone: comparative studies on human and porcine isolated vascular segments.
OBJECTIVE
The vasoconstriction of the renal arteries is frequently considered as a crucial factor for radiocontrast-induced nephropathy. A direct effect of iodinated radiographic contrast medium (RCM) on vascular smooth muscle is supposed to be one component of the vascular response. We studied the effect of the nonionic RCM iomeprol and iohexol on the tonus of isolated human and porcine renal arteries in vitro.


METHODS
In an organ bath renal arterial rings, uncontracted or precontracted by 10 micromol/L phenylephrine were incubated with increasing concentrations (15-103 mg iodine/mL) of iohexol, iomeprol, and mannitol solution isoosmolar to the contrast media. In a part of the preparations the endothelium was destroyed. Human vessels were obtained from tumor nephrectomy specimens of 10 patients.


RESULTS
In human experiments iomeprol and iohexol (P < 0.05) relaxed renal arterial rings whereas mannitol produced concentration-dependent contractions. The relaxation by both contrast media was slightly attenuated upon increasing their concentration. The differences between mannitol solutions and RCM were statistically significant (P < 0.001) at concentrations of 57 mg iodine/mL and higher. Precontracted rings were significantly stronger relaxed by the RCM compared with mannitol (P < 0.001). The contrast medium induced relaxation did not depend on the presence of an intact endothelium (P > 0.05). Experiments with renal arterial segments prepared from swine showed similar results, with stronger relaxations than the human preparations.


CONCLUSIONS
Iomeprol and iohexol relaxed isolated renal arterial segments. These observations are in contradiction with the hypothesis that contrast media induce nephropathy by a direct vasoconstrictive effect on vascular smooth muscle. They do not exclude, however, a reduction of renal blood flow by other factors like liberation of hormones.
Department of Diagnostic Radiology, University Hospital of Saarland, Homburg/Saar, Germany. rauder@med-rz.uni-saarland.de
Michael
M
Uder
Ulrich
U
Humke
Markus
M
Pahl
Angela
A
Jansen
Joser
J
Utz
Bernhard
B
Kramann
D000818:Animals; D003287:Contrast Media; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007472:Iohexol / Q000494:pharmacology*; D007479:Iopamidol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008297:Male; D008353:Mannitol / Q000494:pharmacology; D008875:Middle Aged; D009994:Osmolar Concentration; D012077:Renal Artery / Q000187:drug effects*; D013552:Swine; D014661:Vasoconstriction / Q000187:drug effects
D003287:Contrast Media; C057937:iomeprol; D008353:Mannitol; D007472:Iohexol; D007479:Iopamidol