Influence of iothalamate on renal medullary perfusion and oxygenation in the rat.
OBJECTIVE
To evaluate controversial results regarding the effect of the contrast medium (CM) iothalamate on renal medullary blood flow by applying two different methods simultaneously.


METHODS
The outer medullary blood flow (OMBF) response was estimated using laser-Doppler flowmetry and hydrogen gas wash-out (microelectrodes) simultaneously. Outer medullary oxygen tension (PO2) was measured using Clark type microelectrodes. Iothalamate was injected i.v. at 1600 mg I/kg body weight for 2 min.


RESULTS
CM induced a transient 28% decrease in OMBF as measured with the laser Doppler. The hydrogen gas wash-out rate was reduced by 50%, indicating a reduced perfusion. CM induced a transient 60% reduction in PO2, while renal fluid and electrolyte excretion increased several fold.


CONCLUSIONS
The CM iothalamate reduces outer medullary perfusion as estimated by two different techniques applied simultaneously. The PO2 in the same region was also reduced. Previous controversies regarding the effect of iothalamate on OMBF can be explained by extreme dosage and injection rates greatly exceeding clinical relevance.
Liss
P
P
Department of Oncology, Radiology and Clinical Immunology, Uppsala University, Uppsala, Sweden.
Aukland
K
K
Carlsson
P O
PO
Palm
F
F
Hansell
P
P
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D003287:Contrast Media / Q000008:administration & dosage / Q000494:pharmacology*; D007275:Injections, Intravenous; D007483:Iothalamic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D007679:Kidney Medulla / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D017078:Laser-Doppler Flowmetry; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation / Q000187:drug effects* / Q000502:physiology
D003287:Contrast Media; D007483:Iothalamic Acid