Determination of extrarenal plasma clearance and hepatic uptake of technetium-99m-mercaptoacetyltriglycine in cats.

Abstract

OBJECTIVE:

To determine maximum extrarenal plasma clearance of technetium-99m-mercaptoacetyltriglycine (99mTc-MAG3) and maximum extrarenal hepatic uptake of 99mTc-MAG3 in cats.

ANIMALS:

6 clinically normal adult cats.

PROCEDURES:

Simultaneously, baseline plasma clearance and camera-based uptake of 99mTc-MAG3 were determined in anesthetized cats. Double exponential curves were fitted to plasma clearance data. Injected dose was divided by area under the curve and body weight to determine 99mTc-MAG3 clearance. Regions of interest were drawn around kidneys and liver, and percentage dose uptake was determined 1 to 3 minutes after injection. After bilateral nephrectomy, simultaneous extrarenal plasma clearance and camera-based hepatic uptake of 99mTc-MAG3 were evaluated in each cat.

RESULTS:

Mean +/- SD baseline plasma clearance and extrarenal clearance were 5.29 +/- 0.77 and 0.84 +/- 0.47 mL/min/kg, respectively. Mean extrarenal clearance (as a percentage of baseline plasma clearance) was 16.06 +/- 7.64%. For right, left, and both kidneys, mean percentage dose uptake was 9.42 +/- 2.58, 9.37 +/- 0.86, and 18.79 +/- 2.47%, respectively. Mean hepatic percentage dose uptake before and after nephrectomy was 12.95 +/- 0.93 and 21.47 +/- 2.00%, respectively. Mean percentage change of hepatic uptake after nephrectomy was 166.89 +/- 23.19%.

CONCLUSIONS AND CLINICAL RELEVANCE:

In cats, extrarenal clearance of 99mTc-MAG3 is higher than that of other species; therefore, 99mTc-MAG3 is not useful for estimation of renal function in felids. Evaluation of renal function in cats may be more accurate via camera-based versus plasma clearance-based methods because camera-based studies can discriminate specific organs.

• Authors: William Tod Drost, Mary A McLoughlin, John S Mattoon, Phillip Lerche, Valerie F Samii, Stephen P DiBartola, Dennis J Chew, Paul Y Barthez
• Journal: American journal of veterinary research (Am J Vet Res) Vol. 64 Issue 9 Pg. 1076-80 (Sep 2003) ISSN: 0002-9645 [Print] United States
• PMID: 13677382 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Radiopharmaceuticals
• Technetium Tc 99m Mertiatide

Topics

• Animals
• Area Under Curve
• Cats (blood, metabolism)
• Female
• Kidney (metabolism)
• Liver (metabolism)
• Radioisotope Renography (methods, veterinary)
• Radiopharmaceuticals (pharmacokinetics)
• Renal Plasma Flow (physiology)
• Technetium Tc 99m Mertiatide (pharmacokinetics)