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Isolated interstitial nodal spaces facilitate preferential solute and fluid mixing
Author(s) -
Pannabecker Thomas L,
Layton Anita T
Publication year - 2011
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.25.1_supplement.840.6
Subject(s) - compartment (ship) , lipid microdomain , medullary cavity , anatomy , interstitial fluid , bar (unit) , chemistry , nodal , biophysics , physics , geology , biology , membrane , endocrinology , biochemistry , oceanography , meteorology
Recent anatomic findings indicate that in the upper inner medulla of the rodent kidney, tubules and vessels are organized around clusters of collecting ducts (CDs). Within CD clusters, CDs and some of the ascending vasa recta (AVR) and ascending thin limbs (ATLs), when viewed in transverse sections, form interstitial nodal spaces, which are arrayed at structured intervals throughout the inner medulla. These spaces, or microdomains, are bordered on one side by a single CD, on the opposite side by one or more ATLs, and on the other two sides by AVR. To study the interactions among the CDs, ATLs, and AVR, we have developed a mathematical compartment model, which simulates steady‐state solute exchange through the microdomain at a given inner medullary level. Fluid in all compartments contains Na + , Cl − , urea, and in the microdomain, negative fixed charges that represent macromolecules (e.g., hyaluronan) balanced by Na + . In this simplified model, the nodal compartment is assumed to be incompressible and fluid entry into AVR is assumed to be driven entirely by hydraulic pressure. Model results suggest that the isolated microdomains facilitate solute and fluid mixing among the CDs, ATLs, and AVR, and consequently may play an important role in generating the inner medullary osmotic gradient. Supported in part by NIH grants DK‐89066 and DK‐16294, and NSF grants DMS‐0715021 and IOS‐0952885.