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Role of interstitial nodal spaces in the urine concentrating mechanism of the rat kidney
Author(s) -
Gilbert Rebecca L,
Pannabecker Thomas L.,
Layton Anita T.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.1100.8
Subject(s) - vasa recta , nephron , reabsorption , medullary cavity , anatomy , interstitial space , renal medulla , loop of henle , kidney , interstitial fluid , medulla , compartment (ship) , chemistry , biology , biophysics , geology , endocrinology , oceanography
Recent findings in the upper inner medulla of the rat kidney indicate thin limbs of Henle's loops and vasa recta are arranged in repeating patterns among clusters of collecting ducts (CDs). Within CD clusters an interstitial compartment (interstitial nodal space INS) can be seen in transverse sections of the inner medulla. INSs are delimited by a single CD, one or more ascending thin limbs (ATLs) and ascending vasa recta (AVR). In this study we investigated possible fluid and solute flows among CDs, ATLs and AVR, by examining the spatial interactions of structures that form the INSs. Nephron tubules and vasa recta were identified using immunohistochemistry. Spatial interactions were assessed by quantifying lengths of abutting segments of the rat inner medulla. INS architecture was incorporated into a mathematical model simulating steady‐state solute exchange through INSs at given inner medullary levels. At 400 μm below the outer medullary‐inner medullary border approximately 70% of CD was found to abut the INS. In the INS there are negative fixed charges representing macromolecules, e.g. hyaluronan, balanced by Na + that may promote water reabsorption from CDs. Model results quantify potential fluid and solute fluxes between INSs, nephrons and vessels, and support the hypothesis that INSs serve as fluid and solute mixing chambers that support the inner medullary osmotic gradient. NIH: DK083338 and NSF: DMS0701412