title: Role of intrarenal ANG II in reflex neural stimulation of plasma renin activity and renal sodium reabsorption.
abstract: Renal sympathetic stimulation of plasma renin activity (PRA) and sodium reabsorption was examined in conscious dogs before and during intrarenal angiotensin II (ANG II)-type 1 receptor blockade with losartan (Dup-753) and converting enzyme inhibition. In uninephrectomized dogs, renal function and PRA responses to 14% blood volume depletion (BVD) were measured. BVD was utilized to activate renal sympathetic outflow in the absence of hypotension. In eight vehicle-treated dogs, 14% BVD increased PRA from 1.38 +/- 0.32 to 2.79 +/- 0.66 ng ANG I.ml-1 x h-1 and decreased urinary sodium excretion (UNaV) from 85.1 +/- 11.3 to 45.4 +/- 7.5 mueq/min. During losartan (n = 6) and captopril (n = 5) infusion, plasma renin responses were enhanced in response to 14% BVD (1.93 +/- 0.48 to 5.74 +/- 2.25 and 3.03 +/- 0.73 to 9.19 +/- 1.94 ng ANG I.ml-1 x h-1, respectively), whereas antinatriuretic responses were similar to vehicle-infused dogs. Thus, neurogenic antinatriuresis is not mediated by secondary generation of ANG II, since UNaV decreased similarly to control in all conditions of ANG II blockade. Tonic intrarenal and/or circulating ANG II synthesis of dogs on a normal sodium diet inhibit neurogenic stimulation of renin release, since PRA responses were enhanced after blockade of ANG II.
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee 53226.
authors.forename: L D
authors.initials: LD
authors.lastname: Nelson
authors.forename: J L
authors.initials: JL
authors.lastname: Osborn
mesh_terms: D000042:Absorption; D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology; D001810:Blood Volume; D002216:Captopril / Q000494:pharmacology; D004285:Dogs; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D019808:Losartan; D008297:Male; D012018:Reflex / Q000502:physiology*; D012079:Renal Circulation / Q000187:drug effects; D012083:Renin / Q000097:blood*; D012964:Sodium / Q000493:pharmacokinetics*; D013564:Sympathetic Nervous System / Q000502:physiology*; D013777:Tetrazoles / Q000494:pharmacology; D014661:Vasoconstriction
chemical_list: D001713:Biphenyl Compounds; D007093:Imidazoles; D013777:Tetrazoles; D000804:Angiotensin II; D002216:Captopril; D012964:Sodium; D012083:Renin; D019808:Losartan