Vasopressin increases aqp-cd water channel in the apical membrane
of collecting duct cells without affecting aqp3 distribution in
brattleboro rat.
Yamamoto, Nadashi, Sei Sasaki, Kiyohide Fushimi, Kenichi Ishibashi,
Eishin Yaoita, Katsutoshi Kawasaki, Fumiaki Marumo, Itaru Kihara.
Department of Pathology, Institute of Nephrology, Niigata
University of Medicine, Niigata, and Second Department of Internal
Medicine, Tokyo Medical and Dental University, Tokyo, Japan
APStracts 2:0144C, 1995.
The effect of vasopressin on subcellular localization of AQP-CD and
AQP3 water channels was examined in thirsted Brattleboro rats by
immunohistochemistry and immunoelectron microscopy. AQP-CD was mainly
present in the cytoplasm of the collecting duct cells in association
with cytoplasmic vesicles but was sparse in the apical membrane in
control vehicle-injected rats. In rats given vasopressin 15 min prior
to sacrifice, the number of immunogold particles for AQP-CD in the
apical membrane increased significantly (p<0.002) from 1.8+/-0.2
to 10.0+/-0.4/[mu]m with a significant decrease (p<0.05) of
cytoplasmic labeling from 32.6+/-6.4 to 24.6+/-5.6/[mu][mu]2,
indicating that AQP-CD is the vasopressin-regulated water channel
predicted by $QUOTshuttle hypothesis$QUOT. In contrast, AQP3 was
restricted to the basolateral membrane of the collecting duct cells
and the labeling density of AQP3 was unchanged by vasopressin
-treatment, indicating that AQP3 is constitutively expressed and may
maintain high water permeability of the basolateral membrane.
Received 12 August 1994; accepted in final form 22 February 1995.
APS Manuscript Number C482-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 28 March 1995.