Alteration in water channel aqp-2 by removal of avp stimulation in
collecting duct cells of dehydrated rats.
Saito, Takako, San-E Ishikawa, Sei Sasaki, Nobuya Fujita, Kiyohide
Fushimi, Kouji Okada, Koichi Takeuchi, Atsushi Sakamoto, Shigeo
Ookawara, Toyoji Kaneko, Fumiaki Marumo, and Toshikazu Saito.
Division of Endocrinology and Metabolism, Department of Medicine,
and Department of Anatomy, Jichi Medical School, Tochigi 329-04,
Second Department of Internal Medicine, Tokyo Medical and Dental
University, Tokyo 113, and Ocean Research Institute, Tokyo
University, Tokyo, 164, Japan
APStracts 3:0197F, 1996.
Dehydration increased the expression of aquaporin of collecting duct
(AQP-2) and translocated AQP-2 to the apical plasma membranes from
cytoplasmic vesicles of collecting duct cells. We determined whether
the abrupt decrease in circulating arginine vasopressin (AVP) by
giving excess water affects the expression of AQP-2 mRNA and
subcellular localization of AQP-2 in collecting duct cells of the
dehydrated rats. The 72h water deprivation increased plasma AVP
levels to 3.1 pg/ml and the expression of AQP-2 mRNA by 336% in rats,
which were concomitantly abolished by the 40 ml/kg oral water load. A
50% inhibition of AQP-2 mRNA expression was obtained with 20 min
after the forced water load. In immunohistochemistry and electron
microscopy, the AQP-2 was manifestly present around the apical edge
of collecting duct cells in the 72h dehydrated rats. The AQP-2 was
diffusely translocated into the cytoplasm an hour after the forced
water administration. These results indicate that AVP plays the on
-off regulation of AQP-2 mRNA expression and a majority of AQP-2 is
regulated by the shuttle recycling in the collecting duct cells.
Received 14 February 1996; accepted in final form 28 October
1996.
APS Manuscript Number F49-6.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996