Purpose: The effect on regional renal blood was studied after injection of
nonionic iso-osmolar iotrolan or ionic high-osmolar iothalamate.
Material and Methods: Laser-Doppler flowmetry was used to measure outer med
ullary (OMBF) and superficial cortical blood flow (CBF) simultaneously in a
nesthetized rats. Iotrolan (320 mOsm/kg H2O) was injected i.v. at a dose of
600 mg I/kg b.w. (normal dose) over 2 min or 1,600 (high dose) mg I/kg b.w
. over 2 or 8 min. Iothalamate (2,580 mOsm/kg H2O) was injected i.v, at a d
ose of 1,600 (high dose) or 2,900 (extremely high dose) mg I/kg b.w. over 2
min.
Results: At the normal dose and 2-min injection of iotrolan, OMBF was reduc
ed by 25 +/- 9% over 20 min. The high dose of iotrolan injected over 8 min
resulted in a reduction in OMBF slightly smaller (17 +/- 9%) than that indu
ced by the normal dose but lasting longer (30 min). Compared to the normal
dose, the high dose and fast (2 min) injection of iotrolan resulted in a gr
eater and more prolonged decrease in OMBF (32 +/- 6% lasting 50 min). After
the high dose of iothalamate (1,600 mg I/kg) there was a decrease in OMBF
by 21 +/- 6%, lasting 30 min. An extremely high dose (2,900 mg I/kg b.w.) g
ave a heterogeneous response with a mean increase in OMBF of 48 +/- 24% occ
urring 60 min after the injection.
Conclusion: Iso-osmolar and high-osmolar contrast media (CM), at normal and
high doses, decrease OMBF, while an extremely high dose of iothalamate may
result in an increase. The depression of outer medullary perfusion may hav
e implications for CM-induced acute renal failure in view of the vulnerabil
ity of this region to a decrease in oxygen tension.