Measurement of glomerular filtration rate in anesthetized and conscious rhesus monkeys (Macaca mulatta).
OBJECTIVE
To validate a method to assess glomerular filtration rate (GFR) in conscious monkeys via transcutaneous radiation detection after IV injection of technetium Tc 99m pentatate (99mTc-DTPA).


METHODS
4 healthy rhesus monkeys.


METHODS
On day 1, each monkey was anesthetized, lothalamate sodium I 125 (125l-iothalamate) was administered via continuous rate infusion (0.0037 MBq/min); blood and urine samples were obtained for determination of 125l-iothalamate plasma clearance variables and estimation of GFR. One dose of 99mTc-DTPA (74 MBq/kg, IV) was also administered during the 125l-iothalamate plasma clearance test, and transcutaneous measurements of technetium 99m-emitted radiation were obtained by use of an ambulatory renal monitor (ARM) applied to a brachium of each monkey. Determination of GFR by use of the ARM was repeated on days 8 and 45 in the same monkeys without anesthesia.


RESULTS
Sensitivity, accuracy, and precision of the 2 methods were similar. By use of the ARM, GFR determined by use of the renal rate constant (κGFR) was calculated; the value obtained on day 1 under anesthesia was similar to values determined via 125l-iothalamate plasma clearance testing on the same day, but was 16% to 23% less than that measured on days 8 and 45 in conscious monkeys.


CONCLUSIONS
The ARM method for assessment of GFR was less invasive, faster, and more convenient than the standard clearance method, but yielded comparable results. The need to train animals and size restrictions of the device may limit the use of this technique in other nonhuman animals.
Department of Radiology, Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114, USA. Crabito@partners.org
Carlos A
CA
Rabito
Susan
S
van Tongeren
Paul A
PA
Zavorskas
Alain
A
Stricker-Krongrad
John
J
Robb
Garner T
GT
Haupert
D000758:Anesthesia / Q000662:veterinary*; D000818:Animals; D001132:Arm / Q000502:physiology; D001835:Body Weight; D003243:Consciousness / Q000502:physiology*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D007483:Iothalamic Acid / Q000493:pharmacokinetics; D007668:Kidney / Q000502:physiology; D008253:Macaca mulatta / Q000502:physiology*; D008297:Male; D018670:Monitoring, Ambulatory / Q000379:methods / Q000662:veterinary; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics
D007457:Iodine Radioisotopes; D007483:Iothalamic Acid; D016284:Technetium Tc 99m Pentetate