Excretion Parameters of [I-131]-ortho-iodohippurate in the Perfused Rat Kidney

František Trejtnar (trejtfr@faf.cuni.cz)

Department of Pharmacology and Toxicology, Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Czech Republic

Summary

[¹³¹I]-o-iodohippurate (OIH) is one of the most important radiodiagnostic agent using for renal imaging and renal function measurement. In the study, a comparison renal excretion parameters after bolus and infusion administration was studied using the method of the perfused rat kidney. The rat kidney was perfused with Krebs-Henseleit solution containing bovine albumin, washed rat erythrocytes (6 %) and a mixture of aminoacids in a recirculation regimen at a constant arterial pressure. Experiments showed significant differences between renal elimination of OIH in the perfused rat kidney after adding of the drug as bolus dose or infusion into the perfusate. After the bolus dose, renal clearance OIH was rapidly falling during the perfusion interval. Infusion OIH administration resulted in stable clearance values during the perfusion. The OIH clearance lowering during the perfusion was probably caused due to reaching such low concentrations when reabsorption could begin to play a significant role simultaneously with secretion. Renal clearance was several times higher than inulin clearance. OIH was considerably bound to the proteins in the perfusate. An analysis of renal handling showed that the extent of tubular secretion in the perfused rat kidney was more than 90 %.