Effects of altered physiologic states on clearance and biodistribution of technetium-99m MAG3, iodine-131 OIH, and iodine-125 iothalamate.
Technetium-99m mercaptoacetyltriglycine [( 99mTc]MAG3) is a new renal radiopharmaceutical with biologic properties similar to iodine-131 orthoiodohippuric acid [( 131I]OIH). MAG3 may be used as a replacement for [131I]OIH and/or [99mTc]DTPA. For this reason, we compared the effects of several potential adverse clinical conditions on the clearance and biodistribution of MAG3, OIH and a GFR marker. To simulate renal failure, five mice underwent bilateral renal pedical ligation. Twenty-four hours after surgery they were injected with MAG3 and OIH and killed 2 hr postinjection. Compared to sham operated controls, liver activity for MAG3 and OIH increased from 0.2% to 14.1% and 0.1% to 13.9%, respectively, while intestinal activity increased from 1.3% to 8.9% for MAG3 and 0.2% to 7.7% for OIH. Constant infusion studies were performed in rats to evaluate the effects of increased plasma organic acid levels, mannitol diuresis, dehydration, and acid/base imbalance on the clearance of OIH, MAG3, and [125I]iothalamate. No differences were noted between the OIH and MAG3 clearances following diuresis and dehydration and the differences involving acid/base imbalance were minimal. Dehydration depressed the clearance of [125I]iothalamate more than that of OIH or MAG3. Para-aminohippurate (PAH) infusion inhibited the clearance of MAG3 more than OIH supporting proximal tubular transport for MAG3; PAH had no effect on [125I]iothalamate. In summary HPLC purified MAG3 behaved similarly to OIH under adverse physiologic conditions and the data continue to support the use of MAG3 as a potential clinical substitute for OIH.
Taylor
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Department of Radiology, Emory University School of Medicine, Atlanta, Georgia 30322.
Eshima
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D
D000137:Acid-Base Imbalance / Q000378:metabolism; D000818:Animals; D003681:Dehydration / Q000378:metabolism; D004231:Diuresis; D005260:Female; D007465:Iodohippuric Acid / Q000493:pharmacokinetics*; D007483:Iothalamic Acid / Q000493:pharmacokinetics*; D007676:Kidney Failure, Chronic / Q000000981:diagnostic imaging / Q000378:metabolism; D008297:Male; D051379:Mice; D009842:Oligopeptides / Q000493:pharmacokinetics*; D009942:Organometallic Compounds / Q000493:pharmacokinetics*; D011877:Radionuclide Imaging; D051381:Rats; D013667:Technetium / Q000493:pharmacokinetics*; D017263:Technetium Tc 99m Mertiatide
D009842:Oligopeptides; D009942:Organometallic Compounds; D007465:Iodohippuric Acid; D007483:Iothalamic Acid; D017263:Technetium Tc 99m Mertiatide; D013667:Technetium