Chronic angiotensin-II treatment potentiates HR slowing in Sprague-Dawley rat during acute behavioral stress

Richard E. Hoyt, Richard O. Speakman, David R. Brown, Lisa A. Cassis, Dennis L. Silcox, Chikodi N. Anigbogu, David C. Randall

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

This study examined the effect of 2-week infusion of angiotensin-II (Ang-II; 175. ng/kg/min) via minipump in rats (n=7) upon the mean arterial blood pressure (mBP) and heart rate (HR) response to an acute stress as compared to rats infused with saline (n=7). The acute stress was produced by a classical aversive conditioning paradigm: a 15. s tone (CS. +) followed by a half second tail shock. Baseline mBP in Ang-II infused rats (167.7 ± 21.3. mm Hg; mean ± SD) significantly exceeded that of controls (127.6 ± 13.5. mm Hg). Conversely, baseline HR in the Ang-II infused rats (348 ± 33) was significantly lower than controls (384 ± 19. bpm). The magnitude of the mBP increase during CS. + did not differ between groups, but the HR slowing during CS. + in the Ang-II infused rats (- 13.2 ± 8.9. bpm) was significantly greater than that seen in controls (- 4.2 ± 5.5. bpm). This augmented bradycardia may be inferentially attributed to an accentuated increase in cardiac parasympathetic activity during CS. + in the Ang-II infused rats. The mBP increased above baseline immediately post-shock delivery in controls, but fell in the Ang-II infused rats, perhaps because of a 'ceiling effect' in total vascular resistance. This classical conditioning model of 'acute stress' differs from most stress paradigms in rats in yielding a HR slowing concomitant with a pressor response, and this slowing is potentiated by Ang-II.

Original languageEnglish
Pages (from-to)42-46
Number of pages5
JournalAutonomic Neuroscience: Basic and Clinical
Volume174
Issue number1-2
DOIs
StatePublished - Mar 2013

Bibliographical note

Funding Information:
Supported by grants RO1 NS39774 and HL073085 from the National Institutes of Health .

Funding

Supported by grants RO1 NS39774 and HL073085 from the National Institutes of Health .

FundersFunder number
National Institutes of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)R01HL073085

    Keywords

    • Anxiety
    • Classical Pavlovian conditioning
    • Hypertension
    • Renin angiotensin system (RAS)

    ASJC Scopus subject areas

    • Endocrine and Autonomic Systems
    • Clinical Neurology
    • Cellular and Molecular Neuroscience

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