title: Angiotensin II attenuates the natriuresis of water immersion in humans.
abstract: The hypothesis was tested that suppression of generation of ANG II is one of the mechanisms of the water immersion (WI)-induced natriuresis in humans. In one protocol, eight healthy young males were subjected to 3 h of 1) WI (WI + placebo), 2) WI combined with ANG II infusion of 0.5 ng. kg(-1). min(-1) (WI + ANG II-low), and 3) a seated time control (Con). In another almost identical protocol, 7-10 healthy young males were investigated to delineate the tubular site(s) of action of ANG II by the lithium clearance method (C(Li)) and were on an additional fourth study day subjected to infusion of ANG II at a rate of 1.5 ng. kg(-1). min(-1) (WI + ANG II-high). During WI + placebo, plasma concentration of ANG II decreased from 16 +/- 2 to 8 +/- 1 pg/ml (P < 0.05) and renal sodium excretion increased from 104 +/- 15 to 294 +/- 27 micromol/min (P < 0.05). During WI + ANG II-low, plasma ANG II was not suppressed by WI, and the natriuresis was blunted by 52 +/- 13% (P < 0.05). During WI + ANG II-low and WI + ANG II-high, an increase in C(Li) was prevented that was otherwise observed during WI, and fractional distal reabsorption of sodium was facilitated. In conclusion, maintaining plasma concentration of ANG II unchanged at the level of control attenuates the natriuresis of WI considerably in humans. Therefore, suppression of generation of ANG II is an important mechanism of the natriuresis of WI in humans. Furthermore, infusion of ANG II during WI prevents an otherwise induced increase in C(Li) and facilitates the fractional distal reabsorption of sodium, probably via an effect on aldosterone release.
authors.affiliation: Department of Aviation Medicine, The Heart Centre, The National University Hospital (Rigshospitalet) Dept. 7522, 9 Blegdamsvej, DK-2100 Copenhagen, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Schou
authors.forename: Anders
authors.initials: A
authors.lastname: Gabrielsen
authors.forename: Niels Eske
authors.initials: NE
authors.lastname: Bruun
authors.forename: Peter
authors.initials: P
authors.lastname: Skøtt
authors.forename: Bettina
authors.initials: B
authors.lastname: Pump
authors.forename: Harriet
authors.initials: H
authors.lastname: Dige-Petersen
authors.forename: Erik
authors.initials: E
authors.lastname: Frandsen
authors.forename: Peter
authors.initials: P
authors.lastname: Bie
authors.forename: Jørgen
authors.initials: J
authors.lastname: Warberg
authors.forename: Niels Juel
authors.initials: NJ
authors.lastname: Christensen
authors.forename: Peter
authors.initials: P
authors.lastname: Norsk
mesh_terms: D000328:Adult; D000804:Angiotensin II / Q000494:pharmacology*; D001798:Blood Proteins / Q000032:analysis; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects; D004573:Electrolytes / Q000097:blood; D006728:Hormones / Q000097:blood; D006801:Humans; D007101:Immersion; D007668:Kidney / Q000187:drug effects / Q000502:physiology; D008297:Male; D009318:Natriuresis / Q000187:drug effects*; D014867:Water
chemical_list: D001798:Blood Proteins; D004573:Electrolytes; D006728:Hormones; D014867:Water; D000804:Angiotensin II