title: Vasopressin increases AQP-CD water channel in apical membrane of collecting duct cells in Brattleboro rats.
abstract: 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 before death, 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/microns with a significant decrease (P < 0.05) of cytoplasmic labeling from 32.6 +/- 6.4 to 24.6 +/- 5.6/microns 2, indicating that AQP-CD is the vasopressin-regulated water channel predicted by the "shuttle" hypothesis. 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.
authors.affiliation: Department of Pathology, Niigata University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: S
authors.initials: S
authors.lastname: Sasaki
authors.forename: K
authors.initials: K
authors.lastname: Fushimi
authors.forename: K
authors.initials: K
authors.lastname: Ishibashi
authors.forename: E
authors.initials: E
authors.lastname: Yaoita
authors.forename: K
authors.initials: K
authors.lastname: Kawasaki
authors.forename: F
authors.initials: F
authors.lastname: Marumo
authors.forename: I
authors.initials: I
authors.lastname: Kihara
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D007150:Immunohistochemistry; D007473:Ion Channels / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D007679:Kidney Medulla / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D011817:Rabbits / Q000276:immunology; D051381:Rats; D011910:Rats, Brattleboro; D012016:Reference Values
chemical_list: D000906:Antibodies; C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D007473:Ion Channels; D010455:Peptides; D001127:Arginine Vasopressin