Aquaporin-2 expression in primary cultured rat inner medullary
collecting duct cells.
Maric, Kenan, Alexander Oksche, and Walter Rosenthal,.
1Forschungsinstitut f[umlaut]ur Molekulare Pharmakologie, Alfred
-Kowalke Strasse 4, 10315 Berlin, 2Rudolf-Buchheim-Institut
f[umlaut]ur Pharmakologie, Frankfurter Strasse 107, 35392 Giessen
APStracts 5:0134F, 1998.
Cultured renal epithelial cells rapidly downregulate expression of the
vasopressin-regulated water-channel aquaporin-2 (AQP-2). Our aim was
to define conditions which favour maintenance of AQP-2 expression in
-vitro without genetic manipulation. We show here that primary
cultures of rat inner medullary collecting duct (IMCD) cells retain
AQP-2 expression for at least six days when grown with dibutyryl cAMP
(dbcAMP) supplementation. We also found that coating the culture
dishes with type IV collagen rather than rat-tail collagen retards
AQP-2 downregulation. Immunofluorescence and biochemical studies
indicate a shuttling of AQP-2 bearing vesicles after stimulation with
vasopressin or forskolin. Rab3 proteins, known to be involved in
regulated exocytosis, were detected only in cells grown in the
presence of dbcAMP. Using the adenylyl cyclase assay the functional
integrity of the V2 receptor was confirmed in a broken cell
preparation. Our data show that cyclic AMP supplementation is
sufficient for the maintenance of AQP-2 expression in primary
cultured cells. The model system established here allows the study of
the regulation of genes encoding the antidiuretic machinery at the
cellular level.
Received 4 December 1997; accepted in final form 30 July 1998.
APS Manuscript Number F382-7.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 21 September 1998