Fluorescence dilution technique for measurement of albumin reflection coefficient in isolated glomeruli

Fan Fan, Chun Cheng Andy Chen, Jin Zhang, Carlos M.N. Schreck, Eric A. Roman, Jan M. Williams, Takashi Hirata, Mukut Sharma, Daniel A. Beard, Virginia J. Savin, Richard J. Roman

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


This study describes a high-throughput fluorescence dilution technique to measure the albumin reflection coefficient (σAlb) of isolated glomeruli. Rats were injected with FITC-dextran 250 (75 mg/kg), and the glomeruli were isolated in a 6% BSA solution. Changes in the fluorescence of the glomerulus due to water influx in response to an imposed oncotic gradient was used to determine σAlb. Adjustment of the albumin concentration of the bath from 6 to 5, 4, 3, and 2% produced a 10, 25, 35, and 50% decrease in the fluorescence of the glomeruli. Pretreatment of glomeruli with protamine sulfate (2 mg/ml) or TGF-β1 (10 ng/ml) decreased σAlb from 1 to 0.54 and 0.48, respectively. Water and solute movement were modeled using Kedem-Katchalsky equations, and the measured responses closely fit the predicted behavior, indicating that loss of albumin by solvent drag or diffusion is negligible compared with the movement of water. We also found that σAlb was reduced by 17% in fawn hooded hypertensive rats, 33% in hypertensive Dahl salt-sensitive (SS) rats, 26% in streptozotocin-treated diabetic Dahl SS rats, and 21% in 6-mo old type II diabetic nephropathy rats relative to control Sprague-Dawley rats. The changes in glomerular permeability to albumin were correlated with the degree of proteinuria in these strains. These findings indicate that the fluorescence dilution technique can be used to measure σAlb in populations of isolated glomeruli and provides a means to assess the development of glomerular injury in hypertensive and diabetic models.

Original languageEnglish (US)
Pages (from-to)F1049-F1059
JournalAmerican Journal of Physiology - Renal Physiology
Issue number12
StatePublished - Dec 15 2015
Externally publishedYes


  • Glomerulus
  • Kidney
  • Proteinuria
  • Renal disease
  • Renal hemodynamics

ASJC Scopus subject areas

  • Physiology
  • Urology


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