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Alterations of the renin-angiotensin system at the RVLM of transgenic rats with low brain angiotensinogen

Item Type:Article
Title:Alterations of the renin-angiotensin system at the RVLM of transgenic rats with low brain angiotensinogen
Creators Name:Baltatu, O. and Fontes, M.A.P. and Campagnole-Santos, M.J. and Caligiorni, S. and Ganten, D. and Santos, R.A.S. and Bader, M.
Abstract:The transgenic rats TGR(ASrAOGEN) (TGR) with low levels of brain angiotensinogen were analyzed for cardiovascular reactivity to microinjections of ANG II and angiotensin receptor (AT1) antagonists [CV-11974, AT1 specific; A-779, ANG-(1-7) selective; sarthran, nonspecific] into the rostral ventrolateral medulla (RVLM) of conscious rats. Microinjection of ANG II resulted in a significantly higher increase in the mean arterial pressure (MAP) of TGR than control [Sprague-Dawley (SD)] rats, suggesting an upregulation of ANG II receptors in TGR. CV-11974 produced an increase in MAP of SD but not in TGR rats. A-779 produced a depressor response in SD but not in TGR rats. Conversely, sarthran produced a similar decrease of MAP in both rat groups. The pressor effect of the AT1 antagonist may indicate an inhibitory role of AT1 receptors in the RVLM. On the other hand, ANG-(1-7) appears to have a tonic excitatory role in this region. The altered response to specific angiotensin antagonists in TGR further supports the functionally relevant decrease in angiotensins in the brains of TGR and corroborates the importance of the central renin-angiotensin system in cardiovascular homeostasis.
Keywords:Blood Pressure, Brain Renin-Angiotensin System, Rostral Ventrolateral Medulla, Animals, Rats
Source:American Journal of Physiology Regulatory Integrative and Comparative Physiology
Publisher:American Physiological Society
Page Range:R428-R433
Date:1 January 2001
Official Publication:http://ajpregu.physiology.org/cgi/content/abstract/280/2/R428
PubMed:View item in PubMed

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