Urinary angiotensin II: a marker of renal tissue activity?
The methodology for the collection, extraction, separation and measurement of urinary angiotensin II [the octapeptide, ANG(1-8)] is described. To determine the origin of urinary ANG(1-8), mean arterial pressure, renal hemodynamics and the arterial, renal venous and urinary concentrations of ANG(1-8) were examined prior to and following the constant intra-arterial infusion of tritiated angiotensin II [3H-ANG(1-8)] in graded doses of 0.5, 2.0 and 2.5 ng/kg/min in 5 uninephrectomized, anesthetized female dogs. The infusion of 3H-ANG-(1-8) had no significant effect on mean arterial pressure, glomerular filtration rate, renal blood flow or urine flow rate. The mean concentration of ANG(1-8) in the urine was 3.7 fmol/ml. None or only trace amounts of 3H-ANG(1-8) were detected in the urine in spite of marked increases in renal arterial 3H-ANG(1-8) concentrations. These observations suggest that urinary ANG(1-8) was derived de novo from the intrarenal generation of angiotensin II. In addition, plasma and urinary concentrations of ANG(1-8) were assessed in patients with essential hypertension undergoing treatment with either a diuretic (n = 14) or an angiotensin-converting enzyme inhibitor (n = 14). Although the concentrations of plasma ANG(1-8) responded appropriately to the respective therapies, the urinary excretion of ANG(1-8) was not different following either therapy. These data suggest that ANG(1-8) collected from the urinary bladder may not occur in adequate concentrations to accurately assess the activity of the intrarenal renin-angiotensin system.
Department of Medicine, University of Missouri, Columbia 65212.
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Reams
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Villarreal
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Wu
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Bauer
D000804:Angiotensin II / Q000097:blood / Q000494:pharmacology / Q000652:urine*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D004232:Diuretics / Q000627:therapeutic use; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005919:Glomerular Filtration Rate; D006439:Hemodynamics; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000188:drug therapy / Q000652:urine; D007668:Kidney / Q000378:metabolism / Q000502:physiology*; D014316:Tritium
D000806:Angiotensin-Converting Enzyme Inhibitors; D004232:Diuretics; D014316:Tritium; D000804:Angiotensin II