Angiotensin II modulates conducted vasoconstriction to norepinephrine and local electrical stimulation in rat mesenteric arterioles.
Cardiovasc Res
; 44(1): 176-84, 1999 Oct.
Article
em En
| MEDLINE
| ID: mdl-10615401
ABSTRACT
OBJECTIVE:
Localized application of a vasoconstricting agent onto the wall of an arteriole results not only in a local constriction of the vessel, but also in a conducted vasoconstriction which is detectable more than a millimeter upstream and downstream from the application site. We investigated the effect of intravenous infusion of angiotensin II (ANG II), losartan or methoxamine on conducted vasoconstriction to local application of norepinephrine (NE) or local electrical stimulation onto the surface of rat mesenteric arterioles in vivo.METHODS:
In anesthetized male Wistar rats (n = 43) NE (0.1 mM) or a local depolarizing current was continuously applied onto mesenteric arterioles using micropipettes. Local and conducted vasoconstriction was measured using videomicroscopy. Conducted responses were measured 200-1000 microns upstream from the application site.RESULTS:
Systemic infusion of ANG II (4 ng/min) raised mean arterial blood pressure by 6 +/- 2 mm Hg and increased the conducted but not the local vasoconstrictor response to NE (P < 0.02). Infusion of the alpha 1-agonist methoxamine raised blood pressure to the same extent, but did not change conducted vasoconstriction significantly. Blockade of endogenous ANG II by infusion of the AT1-receptor blocker losartan decreased conducted vasoconstriction to NE (P < 0.03). In parallel with the findings using NE, ANG II increased (P < 0.05) and losartan decreased (P < 0.01) conducted vasoconstriction when local electrical stimulation was used to initiate the conducted vascular response.CONCLUSION:
The findings suggest that conducted vasoconstriction to NE and local electrical stimulation in rat mesenteric arterioles are modulated by ANG II, an increase in the plasma levels of ANG II increasing conducted vasoconstriction.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Limite:
Animals
Idioma:
En
Ano de publicação:
1999
Tipo de documento:
Article