Chronic Angiotensin II Treatment potentiates HR slowing in Sprague-Dawley Rat during Acute Behavioral Stress
Date
2013
Authors
Speakman, R.O
Brown, D.R.
Cassis, L.A.
Silcox, D.L.
Anigbogu, C. N.
Randall, D.C.
Hoyt, R.E.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier B.V.
Abstract
This study examined the effect of2-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 magnitudeofthemBPincreaseduringCS+didnotdifferbetweengroups,buttheHRslowingduringCS+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.
Description
Staff publications
Keywords
Classical pavlovian conditioning , Anxiety , Hypertension , Renin angiotensin system , Research Subject Categories::MEDICINE
Citation
Hoyt, R.E. [Et...al] (2013). Chronic Angiotensin II Treatment potentiates HR slowing in Sprague-Dawley Rat during Acute Behavioral Stress. Autonomic neuroscience: Basic and Clinical 174 (1-2), 42-46.