title: Dietary sodium intake modulates renal excretory responses to intrarenal angiotensin (1-7) administration in anesthetized rats.
abstract: Angiotensin II at the kidney regulates renal hemodynamic and excretory function, but the actions of an alternative metabolite, angiotensin (1-7), are less clear. This study investigated how manipulation of dietary sodium intake influenced the renal hemodynamic and excretory responses to intrarenal administration of angiotensin (1-7). Renal interstitial infusion of angiotensin (1-7) in anesthetized rats fed a normal salt intake had minimal effects on glomerular filtration rate but caused dose-related increases in urine flow and absolute and fractional sodium excretions ranging from 150 to 200%. In rats maintained for 2 wk on a low-sodium diet angiotensin (1-7) increased glomerular filtration rate by some 45%, but the diuretic and natriuretic responses were enhanced compared with those in rats on a normal sodium intake. By contrast, renal interstitial infusion of angiotensin (1-7) in rats maintained on a high-sodium intake had no effect on glomerular filtration rate, whereas the diuresis and natriuresis was markedly attenuated compared with those in rats fed either a normal or low-sodium diet. Plasma renin and angiotensin (1-7) were highest in the rats on the low-sodium diet and depressed in the rats on a high-sodium diet. These findings demonstrate that the renal hemodynamic and excretory responses to locally administered angiotensin (1-7) is dependent on the level of sodium intake and indirectly on the degree of activation of the renin-angiotensin system. The exact way in which angiotensin (1-7) exerts its effects may be dependent on the prevailing levels of angiotensin II and its receptor expression.
authors.affiliation: Dept. of Physiology, Western Gateway Bldg., Univ. College Cork, Cork, Republic of Ireland.
authors.forename: Julie
authors.initials: J
authors.lastname: O'Neill
authors.forename: Alan
authors.initials: A
authors.lastname: Corbett
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Johns
mesh_terms: D018681:Anesthetics, General; D000803:Angiotensin I / Q000008:administration & dosage*; D000818:Animals; D005919:Glomerular Filtration Rate / Q000187:drug effects* / Q000502:physiology*; D007668:Kidney / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D010446:Peptide Fragments / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar; D012079:Renal Circulation / Q000187:drug effects / Q000502:physiology; D012982:Sodium, Dietary / Q000008:administration & dosage* / Q000493:pharmacokinetics*
chemical_list: D018681:Anesthetics, General; D010446:Peptide Fragments; D012982:Sodium, Dietary; D000803:Angiotensin I; C118790:angiotensin I (1-7)