Involvement of AT2 receptors at NRVL in tonic baroreflex suppression by endogenous angiotensins

The American Journal of Physiology
K S LinS H Chan

Abstract

We evaluated the role of endogenous angiotensin II and III (ANG II and ANG III) at the rostral nucleus reticularis ventrolateralis (NRVL) in the modulation of baroreceptor reflex (BRR) response and the subtype of angiotensin receptors involved in this process. Adult male Sprague-Dawley rats anesthetized and maintained with pentobarbital sodium were used. Exogenous application of ANG II or ANG III (10, 20, or 40 pmol) by bilateral microinjection into the NRVL significantly suppressed the BRR response to transient hypertension induced by phenylephrine (5 micrograms/kg i.v.). The suppressive effect of ANG II (20 pmol) was reversed by an equimolar dose (1.6 nmol) of its peptide antagonist, [Sar1, Ile8]ANG II, and the nonpeptide antagonists for AT1 and AT2 receptors, losartan and PD-123319, respectively. On the other hand, the inhibitory action of ANG III (20 pmol) was blunted by its peptide antagonist. [Ile7]ANG III or PD-123319, but not by losartan. Blocking the endogenous activity of the angiotensins by microinjection into the bilateral NRVL of [Sar1, Ile8]ANG II, [Ile7]ANG III, or PD-123319 elicited an appreciable enhancement of the BRR response, whereas losartan produced minimal effect. These results suggest that, under physiol...Continue Reading

Citations

Nov 22, 2000·American Journal of Physiology. Heart and Circulatory Physiology·S Ito, A F Sved
Sep 20, 2000·American Journal of Physiology. Heart and Circulatory Physiology·S NosakaJ Maruyama
Aug 10, 2019·Pflügers Archiv : European journal of physiology·Willian Costa-FerreiraCarlos C Crestani
Mar 30, 2005·Autonomic Neuroscience : Basic & Clinical·Rong MaWei Wang

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