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Molecular sieving of albumin by the ascending vasa recta wall

T L Pallone1

  • 1Division of Nephrology, M. S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.

The Journal of Clinical Investigation
|July 1, 1992
PubMed

Insights

Albumin transport in the kidney

Area of Science:

  • Renal Physiology
  • Vascular Biology
  • Protein Transport

Background:

  • An extravascular albumin pool exists in the renal medullary interstitium.
  • The precise mechanism of albumin transport across renal microvasculature remains unclear.

Purpose of the Study:

  • To investigate molecular sieving of albumin by ascending vasa recta (AVR) in vivo.
  • To quantify albumin transport influenced by volume flux.

Main Methods:

  • In vivo microperfusion of descending (DVR) and ascending vasa recta (AVR) in rats.
  • Utilized 125I-labeled albumin and FITC-labeled dextran (FITC-Dx) to assess transport.
  • Manipulated transcapillary volume flux (Jv) to study albumin movement.

Main Results:

  • Albumin diffusion was negligible when volume flux was zero.
  • Increased volume flux significantly altered albumin and dextran ratios in AVR.
  • Albumin transport across AVR is primarily governed by solvent drag.

Conclusions:

  • Ascending vasa recta exhibit molecular sieving properties for albumin.
  • Solvent drag is the main mechanism for albumin transport in AVR.
  • The reflection coefficient for albumin in AVR is estimated at 0.78.

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