Modulation of reflex function by endogenous angiotensins in older transgenic rats with low glial angiotensinogen

Amy C. Arnold, Atsushi Sakima, Detlev Ganten, Carlos M. Ferrario, Debra I. Diz

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Age-related impairments in baroreflex sensitivity in Sprague-Dawley rats are associated with low solitary tract nucleus content of angiotensin-(1-7). However, transgenic rats with low-brain angiotensinogen resulting from glial overexpression of an antisense oligonucleotide to angiotensinogen (ASrAOGEN) are spared age-related declines in cardiovascular function characteristic of Sprague-Dawley rats. We examine whether cardiovascular and reflex actions of angiotensin-(1-7) persist in the solitary tract nucleus of older (16 to 22 months) ASrAOGEN rats. Baroreflex sensitivity for control of heart rate and chemosensitive vagal afferent activation in response to phenylbiguanide were measured before and after bilateral microinjection of the angiotensin II type 1 receptor antagonist candesartan and angiotensin-(1-7) receptor antagonist (D-Ala)-angiotensin-(1-7) in urethane/chloralose-anesthetized rats. In older anesthetized ASrAOGEN rats, candesartan had no effect, whereas (D-Ala)-angiotensin-(1-7) significantly reduced baroreflex sensitivity (1.80±0.43 versus 0.50±0.17 ms/mm Hg). Phenylbiguanide responses were attenuated by injection of candesartan (-79±6 versus -55±12 mm Hg and -277±12 versus -156±27 bpm; P<0.05). In addition, resting blood pressure was reduced by injection of candesartan or (D-Ala)-angiotensin-(1-7). Within the solitary tract nucleus of older ASrAOGEN rats, it appears that glial angiotensinogen is the main source of angiotensin II attenuation of baroreflex sensitivity; endogenous angiotensin-(1-7) from nonglial sources enhances baroreflex sensitivity; nonglial sources of angiotensin II contribute to chemosensitive vagal afferent activation; and receptors for both peptides modulate resting arterial pressure under anesthesia. These results suggest a novel mechanism for the preservation of baroreflex sensitivity during aging.

Original languageEnglish (US)
Pages (from-to)1326-1331
Number of pages6
JournalHypertension
Volume51
Issue number5
DOIs
StatePublished - May 1 2008

Fingerprint

Transgenic Rats
Angiotensinogen
Angiotensins
Baroreflex
Neuroglia
Reflex
Solitary Nucleus
Angiotensin II
Sprague Dawley Rats
Angiotensin II Type 1 Receptor Blockers
Chloralose
Injections
Peptide Receptors
Antisense Oligonucleotides
Urethane
Microinjections
angiotensin I (1-7)
Arterial Pressure
Anesthesia
Heart Rate

All Science Journal Classification (ASJC) codes

  • Internal Medicine

Cite this

Arnold, Amy C. ; Sakima, Atsushi ; Ganten, Detlev ; Ferrario, Carlos M. ; Diz, Debra I. / Modulation of reflex function by endogenous angiotensins in older transgenic rats with low glial angiotensinogen. In: Hypertension. 2008 ; Vol. 51, No. 5. pp. 1326-1331.
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Modulation of reflex function by endogenous angiotensins in older transgenic rats with low glial angiotensinogen. / Arnold, Amy C.; Sakima, Atsushi; Ganten, Detlev; Ferrario, Carlos M.; Diz, Debra I.

In: Hypertension, Vol. 51, No. 5, 01.05.2008, p. 1326-1331.

Research output: Contribution to journalArticle

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