Developmental expression of aquaporin 1 in the rat renal
vasculature..
Kim, Jin, Wan-Young Kim, Ki-Hwan Han, Mark Knepper, Soren Nielsen, and
Kirsten M. Madsen.
Department of Anatomy, Catholic University Medical College, Seoul,
Korea; Laboratory of Kidney and Electrolyte Metabolism, National
Heart, Lung, and Blood Institute, National Institutes of Health,
Bethesda, MD 20892-0951, USA; Department of Cell Biology, Institute
of Anatomy, University of Aarhus, DK-8000 Aarhus, Denmark; and
Division of Nephrology, Hypertension and Transplantation, University
of Florida College of Medicine, Gainesville, FL 32610-0224
APStracts 5:0205F, 1998.
Aquaporin 1 (AQP-1) is a water channel protein that is constitutively
expressed in renal proximal tubule and descending thin limb cells as
well as in endothelial cells of the descending vasa recta. Studies in
the developing rat kidney have demonstrated that AQP-1 is expressed
in renal tubules before birth. However, nothing is known about the
expression of AQP-1 in the renal vasculature during kidney
development. The purpose of this study was to establish the
distribution of AQP-1 in the renal vasculature of the developing rat
kidney and follow the differentiation of the vascular system during
kidney development. Kidneys from 16-, 17-, 18- and 20-day-old fetuses
and 1-, 4-, 7-, 14-, 21- and 28-day-old pups were preserved and
processed for immunohistochemical studies using a preembedding
immunoperoxidase procedure. AQP-1 immunoreactivity was detected using
affinity-purified rabbit polyclonal antibodies to AQP-1. AQP-1 was
expressed throughout the arterial portion of the renal vasculature of
the fetal and neonatal kidney from gestational age 17 to one week
after birth. AQP-1 immunoreactivity gradually disappeared from the
renal vasculature between one and two weeks of age and remained only
in the descending vasa recta. In contrast, AQP-1 immunoreactivity was
not observed in lymphatic vessels until three weeks of age and
persisted in the adult kidney. AQP-1 was also expressed in a
population of interstitial cells in the terminal part of the renal
papilla at 3 weeks of age as well as in the adult kidney. The
transient expression of AQP-1 in the arterial portion of the renal
vasculature in the developing rat kidney suggests that AQP-1 is
important for fluid equilibrium and/or drainage in the developing
kidney or, alternatively, plays a role in the regulation of growth
and/or branching of the vascular tree during kidney development.
Received 26 August 1998; accepted in final form 17 November 1998.
APS Manuscript Number F220-8.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 9 December 1998