Related Experiment Video
Updated: May 26, 2026

Culturing Primary Rat Inner Medullary Collecting Duct Cells
Published on: June 21, 2013
Daily variance of urinary excretion of AQP2 determined by sandwich ELISA method
Sei Sasaki1, Yasukazu Ohmoto, Toyoki Mori
1Department of Nephrology, Tokyo Medical and Dental University, Tokyo, Japan. ssasaki.kid@tmd.ac.jp
Background:
Urinary excretion of aquaporin 2 (AQP2) is a useful marker of kidney collecting duct function. A specific and convenient method to measure AQP2 in human urine would help to treat water balance disorders. It is unknown whether urinary excretion of AQP2 shows any daily variance.
Methods:
A sandwich enzyme-linked immunosorbent assay (ELISA) method for AQP2 was established using two different kinds of antibodies, and its sensitivity and specificity were examined. Daily variance of urinary excretion of AQP2 and responses to acute water load were examined.
Results:
The established ELISA specifically detected urine AQP2 with high sensitivity (detected as low as 0.34 pmol/mL). Urinary excretion of AQP2 did not show daily variance between 9 a.m. and 9 p.m. in healthy subjects.
Conclusions:
The developed ELISA method using two different antibodies is convenient and highly sensitive, and could be useful in clinical practice. Urinary excretion of AQP2 is relatively constant from morning to night, and spot urine sampling at any time during this time period does not affect the results.
Related Concept Videos
One-Compartment Open Model: Urinary Excretion Data and Determination of k
Aquaporins
Renal Drug Clearance: Comparison Between Renal Excretion Methods
Renal clearance is often associated with the renal glomerular filtration rate (GFR), which represents the rate at which plasma is filtered through the glomeruli in the kidney. When drug reabsorption is minimal and there is no active secretion, renal clearance is closely related to the...

