Rapid diagnosis and quantification of acute kidney injury using fluorescent ratio-metric determination of glomerular filtration rate in the rat

Am J Physiol Renal Physiol. 2010 Nov;299(5):F1048-55. doi: 10.1152/ajprenal.00691.2009. Epub 2010 Aug 4.


The rapid diagnosis and quantification of acute kidney injury (AKI) severity remain high clinical priorities. By combining intravital fluorescent ratiometric two-photon kidney imaging and the two-compartment pharmacokinetics model, we demonstrate that rapid quantification of glomerular filtration rate (GFR) can be achieved in physiologic and AKI rat kidney models. Using a bolus infusion of a mixture of FITC-inulin and a 500-kDa Texas Red dextran, a full spectrum of GFR values, ranging from 0.17 to 1.12 ml·min(-1)·100 g(-1), was obtained. The GFR values thus determined correlated well with values obtained by the standard 2-h inulin infusion clearance method with a Pearson's correlation coefficient of 0.85. In addition, postischemia deterioration was studied by measuring GFR using the two-photon approach during 24 h following a 45-min bilateral ischemia clamp model. The GFR was found to decline sharply during the initial 4 h followed by a nadir with little sign of rising over the ensuing 24-h period. Moreover, a FITC-labeled 5-kDa dextran was identified as having nearly identical filtration characteristics as FITC-inulin, but had markedly increased fluorescent intensity, thus minimizing the quantity needed for individual studies. The technique reported allows for very rapid GFR determinations, within 10-15 min, based on plasma clearance of a freely filtered fluorescence probe, instead of a prolonged one-compartment interstitial space reporter molecule clearance employed by other technologies.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acute Kidney Injury / chemically induced
  • Acute Kidney Injury / diagnosis*
  • Acute Kidney Injury / pathology
  • Algorithms
  • Animals
  • Data Interpretation, Statistical
  • Female
  • Fluorescein-5-isothiocyanate
  • Gentamicins
  • Glomerular Filtration Rate / physiology*
  • Image Processing, Computer-Assisted
  • Inulin / metabolism
  • Ischemia / pathology
  • Kidney Function Tests / methods*
  • Lipopolysaccharides
  • Male
  • Microscopy, Confocal
  • Protein Synthesis Inhibitors
  • Rats
  • Rats, Sprague-Dawley


  • Gentamicins
  • Lipopolysaccharides
  • Protein Synthesis Inhibitors
  • Inulin
  • Fluorescein-5-isothiocyanate