The role of angiotensin(1-7) in renal vasculature of the rat.
OBJECTIVE
Angiotensin(1-7) is an active component of the renin-angiotensin-aldosterone system. Its exact role in renal vascular function is unclear. We therefore studied the effects of angiotensin(1-7) on the renal vasculature in vitro and in vivo.


METHODS
Isolated small renal arteries were studied in an arteriograph system by constructing concentration-response curves to angiotensin II, without and with angiotensin(1-7). In isolated perfused kidneys, the response of angiotensin II on renal vascular resistance was measured without and with angiotensin(1-7). The influence of angiotensin(1-7) on angiotensin II-induced glomerular afferent and efferent constriction was assessed with intravital microscopy in vivo under anaesthesia. In freely moving rats, we studied the effect of angiotensin(1-7) on angiotensin II-induced reduction of renal blood flow with an electromagnetic flow probe.


RESULTS
Angiotensin(1-7) alone had no effect on the renal vasculature in any of the experiments. In vitro, angiotensin(1-7) antagonized angiotensin-II-induced constriction of isolated renal arteries (9.71 +/- 1.21 and 3.20 +/- 0.57%, for control and angiotensin(1-7) pre-treated arteries, respectively; P < 0.0005). In isolated perfused kidneys, angiotensin(1-7) reduced the angiotensin II response (100 +/- 16.6 versus 72.6 +/- 15.6%, P < 0.05) and shifted the angiotensin II dose-response curve rightward (pEC50, 6.69 +/- 0.19 and 6.26 +/- 0.12 for control and angiotensin(1-7) pre-treated kidneys, respectively; P < 0.05). Angiotensin(1-7), however, was devoid of effects on angiotensin-II-induced constriction of glomerular afferent and efferent arterioles and on angiotensin-II-induced renal blood flow reduction in freely moving rats in vivo.


CONCLUSIONS
Angiotensin(1-7) antagonizes angiotensin II in renal vessels in vitro, but does not appear to have a major function in normal physiological regulation of renal vascular function in vivo.
van der Wouden
Els A
EA
Department of Clinical Pharmacology, Groningen University Institute for Drug Exploration, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Ochodnický
Peter
P
van Dokkum
Richard Pe
RP
Roks
Anton Jm
AJ
Deelman
Leo E
LE
de Zeeuw
Dick
D
Henning
Robert H
RH
D000758:Anesthesia; D000803:Angiotensin I / Q000494:pharmacology*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001160:Arterioles / Q000187:drug effects; D066298:In Vitro Techniques; D007678:Kidney Glomerulus / Q000187:drug effects; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012077:Renal Artery / Q000187:drug effects*; D012079:Renal Circulation / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000959:Antihypertensive Agents; D010446:Peptide Fragments; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D000803:Angiotensin I; C118790:angiotensin I (1-7)