The effects of collecting duct amdboctive n[alpha]cl reabsorption
and inner medulla anatomy on the renal concentrating mechanism.
Wang, Xianqun, and Anthony S. Wexler.
Department of Mechanical Engineering, University of Delaware,
Newark, DE 19716-3140
APStracts 2:0202F, 1995.
Recent measurements have pointed out two flaws in the 3-dimensional
model of Wexler et al., 1991 (Am. J. Physiol. 260:F368-383). First,
the representation of the inner medulla incorporates an exaggerated
radial separation between tubules, vessels, and collecting ducts, and
second, the hydraulic permeability in the upper portion of the inner
medullary collecting ducts was erroneously set to zero. In the
current work, we explore the role of collecting duct hydraulic
permeability and anatomical heterogeneity via mathematical modeling.
The model predicts concentrated urine for measured values of the
hydraulic permeability and homogeneous lower inner medulla as long as
net active NaCl reabsorption is incorporated in the upper inner
medullary collecting duct epithelium. This new 3-dimensional model
results in two recycling paths. The upper portion of the inner
medulla recycles NaCl whereas the lower portion recycles urea.
Received 17 October 1994; accepted in final form 13 November
1995.
APS Manuscript Number F372-4.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95