Can continuous intraperitoneal infusion of 125I-iothalamate and 131I-hippuran be used for measurement of GFR in conscious rats?
We previously described a method to measure GFR in conscious spontaneously voiding rats. This method circumvents the need for anesthesia and for bladder instrumentation. It's main principle is the correction of renal 125I-iothalamate clearance for incomplete urine collection by the ratio of plasma and renal clearance of co-infused 131I-Hippuran. A disadvantage of this technique is the requirement of an intra-arterial catheter for infusion of the renal function tracers. We therefore tested whether intraperitoneal infusion of 125I-iothalamate and 131I-Hippuran can be used for such a GFR measurement in conscious spontaneously voiding rats. We found that during intraperitoneal administration, stable plasma levels of 131I-Hippuran could be obtained. However, urinary recovery of 131I-Hippuran was incomplete (66 +/- 32%), leading to a significant overestimation of GFR by 140 +/- 13% in comparison with the GFR measured by the intra-arterial technique. Thus intraperitoneal infusion of renal function tracers cannot replace intra-arterial infusion.
de Vries
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PA
Groningen Institute for Drug studies (GIDS), Department of Internal Medicine, University Hospital, The Netherlands.
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de Jong
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de Zeeuw
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D000818:Animals; D002408:Catheters, Indwelling; D003287:Contrast Media / Q000008:administration & dosage*; D005919:Glomerular Filtration Rate / Q000502:physiology*; D007261:Infusions, Intra-Arterial; D007263:Infusions, Parenteral; D007457:Iodine Radioisotopes; D007465:Iodohippuric Acid / Q000008:administration & dosage; D007483:Iothalamic Acid / Q000008:administration & dosage; D007678:Kidney Glomerulus / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D003287:Contrast Media; D007457:Iodine Radioisotopes; D007465:Iodohippuric Acid; D007483:Iothalamic Acid