title: Angiotensin-II promotes Na+ uptake in larval zebrafish, Danio rerio, in acidic and ion-poor water.
abstract: The contribution of the renin-angiotensin system (RAS) to Na(+) uptake was investigated in larval zebrafish (Danio rerio). At 4 days post fertilization (dpf), the level of whole-body angiotensin-II (ANG-II) was significantly increased after 1- or 3-h exposure to acidic (pH=4.0) or ion-poor water (20-fold dilution of Ottawa tapwater), suggesting rapid activation of the RAS. Long-term (24 h) treatment of 3 dpf larvae with ANG-I or ANG-II significantly increased Na(+) uptake which was accompanied by an increase in mRNA expression of the Na(+)-Cl(-) cotransporter (zslc12a10.2). Induction of Na(+) uptake by exposure to ANG-I was blocked by simultaneously treating larvae with lisinopril (an angiotensin-converting enzyme inhibitor). Acute (2 h) exposure to acidic water or ion-poor water led to significant increase in Na(+) uptake which was partially blocked by the ANG-II receptor antagonist, telmisartan. Consistent with these data, translational knockdown of renin prevented the stimulation of Na(+) uptake following exposure to acidic or ion-poor water. The lack of any effects of pharmacological inhibition (using RU486), or knockdown of glucocorticoid receptors on the stimulation of Na(+) uptake during acute exposure to acidic or ion-poor environments, indicates that the acute effects of RAS occur independently of cortisol signaling. The results of this study demonstrate that the RAS is involved in Na(+) homeostasis in larval zebrafish.
authors.affiliation: Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, Ontario, Canada K1N 6N5 Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kumai
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Bernier
authors.forename: Steve F
authors.initials: SF
authors.lastname: Perry
mesh_terms: D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012084:Renin-Angiotensin System; D012964:Sodium / Q000378:metabolism*; D064486:Solute Carrier Family 12, Member 3 / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D014867:Water / Q000737:chemistry*; D015027:Zebrafish / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D064486:Solute Carrier Family 12, Member 3; D029961:Zebrafish Proteins; D014867:Water; D000804:Angiotensin II; D012964:Sodium
keywords: acidic water; angiotensin-II; cortisol; ion-poor water; osmoregulation; zebrafish