title: Role of the renin-angiotensin system in regulation and autoregulation of renal blood flow.
abstract: The role for ANG II in renal blood flow (RBF) autoregulation is unsettled. The present study was designed to test the effect of clamping plasma ANG II concentrations ([ANG II]) by simultaneous infusion of the angiotensin-converting enzyme inhibitor captopril and ANG II on RBF autoregulation in halothane-anesthetized Sprague-Dawley rats. Autoregulation was defined as the RBF response to acute changes in renal perfusion pressure (RPP). Regulation was defined as changes in RBF during long-lasting changes in RPP. The results showed that a prolonged reduction of RPP reset the lower limit of autoregulation from 85 +/- 1 to 73 +/- 2 mmHg (P < 0.05) and regulated RBF to a lower level. Reduction of RPP to just above the lower limit of autoregulation (88 mmHg) induced regulation of RBF to a lower level within 10 min. Clamping [ANG II] per se reset the lower limit of autoregulation to 62 +/- 5 mmHg. In this case, reduction in RPP to 50 mmHg did not induce a downregulation of RBF. We conclude that ANG II plays an important role in the resetting of the autoregulation limits. The ability to regulate RBF to a new level as a response to changes in RPP also depends on changes in [ANG II].
authors.affiliation: Department of Medical Physiology, Division of Renal and Cardiovascular Research, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen N, Denmark. cmehlin@mfi.ku.dk
authors.forename: C M
authors.initials: CM
authors.lastname: Sorensen
authors.forename: P P
authors.initials: PP
authors.lastname: Leyssac
authors.forename: O
authors.initials: O
authors.lastname: Skott
authors.forename: N H
authors.initials: NH
authors.lastname: Holstein-Rathlou
mesh_terms: D000804:Angiotensin II / Q000097:blood / Q000494:pharmacology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002216:Captopril / Q000494:pharmacology; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012079:Renal Circulation / Q000187:drug effects / Q000502:physiology*; D012084:Renin-Angiotensin System / Q000502:physiology*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D000804:Angiotensin II; D002216:Captopril