Effects of angiotensin-(1-7) and other bioactive components of the renin-angiotensin system on vascular resistance and noradrenaline release in rat kidney.
OBJECTIVE
Angiotensin (Ang) is broken down enzymatically to several different metabolites which, in addition to Ang II, may have important biological effects in the kidney. This study investigates the role of Ang metabolites on vascular resistance and noradrenaline release in the rat kidney.


RESULTS
In rat isolated kidney Ang I, Ang II, Ang III, Ang IV and des-Asp-Ang I induced pressor responses and enhanced noradrenaline release to renal nerve stimulation (RNS) in an concentration-dependent manner, with the following rank order of potency (EC(50)): Ang II >or= Ang III > Ang I = des-Asp-Ang I > Ang IV. All effects were blocked by the AT(1)-receptor antagonist EXP 3174 (0.1 micromol/l) but not by the AT(2)-receptor antagonist PD 123319 (1 micromol/l). Angiotensin-converting enzyme (ACE) inhibition by captopril (10 micromol/l) abolished the effect of Ang I and des-Asp-Ang I but had no influence on the effect of the other metabolites. Ang-(1-7) blocked the effects of Ang I and Ang II, being 10 times more potent against Ang I than Ang II. The selective Ang-(1-7) receptor blocker d-Ala7-Ang-(1-7) (10 micromol/l) did not influence the inhibitory effects of Ang-(1-7). Ang-(1-7) (10 micromol/l) by itself had no influence on vascular resistance and RNS-induced noradrenaline release.


CONCLUSIONS
Ang I, Ang II, Ang III, Ang IV and des-Asp-Ang I regulate renal vascular resistance and noradrenaline release by activation of AT(1) receptors. In the case of Ang I and des-Asp-Ang I this depends on conversion by ACE. Ang-(1-7) may act as a potent endogenous inhibitor/antagonist of ACE and the AT(1)-receptors, respectively.
Stegbauer
Johannes
J
Department of Internal Medicine I, Marienhospital Herne, Ruhr-University Bochum, Herne, Germany.
Vonend
Oliver
O
Oberhauser
Vitus
V
Rump
Lars Christian
LC
D000626:Aminopeptidases / Q000037:antagonists & inhibitors; D000803:Angiotensin I / Q000494:pharmacology*; D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers; D057912:Angiotensin II Type 2 Receptor Blockers; D000805:Angiotensin III / Q000494:pharmacology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D011921:Rats, Inbred WKY; D012084:Renin-Angiotensin System / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D047228:Angiotensin II Type 1 Receptor Blockers; D057912:Angiotensin II Type 2 Receptor Blockers; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D010446:Peptide Fragments; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D000805:Angiotensin III; C012877:angiotensin II, des-Asp(1)-des-Arg(2)-Ile(5)-; D000803:Angiotensin I; D000626:Aminopeptidases; C118790:angiotensin I (1-7); D009638:Norepinephrine