Volume 4, Number 2, June 2003

Biphasic effects of angiotensin (1-7) and its interactions with angiotensin II in rat aorta
Ion Haulica, Walther Bild, Christian N Mihaila, Teodor Ionita, Corneliu P Boisteanu, Bogdan Neagu

Using isolated rat aortic rings perfused with Krebs-Henseleit saline, the vascular effects of angiotensin (1-7) (Ang [1-7]) and its interactions with angiotensin II (Ang II) were investigated.
Ang (1-7) induced endothelium-dependent relaxation and vasodilating effects in preparations precontracted with phenylephrine. Without preconstriction, Ang (1-7) at high doses (10^-6–10^-5 M) produced either a significant inhibition of Ang II-induced vasoconstriction or a non-tachyphylactic vasopressor response. While losartan inhibited the vasoconstriction induced by Ang (1-7), A779 blocked only its relaxation. Unlike losartan, blockade of AT₂-receptors with PD 123319 had no effect. Taking into account the biphasic effects of angiotensin (1-7), we propose that it is one of the active components of the renin-angiotensin system, which is involved as a modulator both in the counter-regulatory actions of Ang II and in the self-regulation of its own vasodilating effects.

JRAAS 2003;4:124-128.

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