What question did this study set out to answer?

To determine whether central administration of angiotensin II alters the cardioinhibitory baroreceptor reflex evoked by acute norepinephrine-induced blood pressure elevations.

May 28, 2008Pharmacology

Norepinephrine-Induced Reflex Bradycardia after Central Administration of Angiotensin II

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Why the study?

Does central administration of angiotensin II alter norepinephrine-induced reflex bradycardia in cats?

Population

Cats (unanesthetized brain, spinal cats)

Comparison

Angiotensin II administered intravertebrally… vs Baseline/control responses to norepinephrine

Design

Preclinical

Authors

WSWalter B. SeversPenn State Milton S. Hershey Medical Center JSJoan Y. Summy‐LongPenn State Milton S. Hershey Medical Center

Discussion

Member takes

Implication

Central angiotensin II raises basal BP without blunting reflex bradycardia in cats; hypothesis-generating for central RAS effects on human baroreflex.

Key Points

To determine whether central administration of angiotensin II alters the cardioinhibitory baroreceptor reflex evoked by acute norepinephrine-induced blood pressure elevations.
Administered angiotensin II to cats intravertebrally (10 ng/kg/min), into a lateral cerebroventricle (0.4 µg/min), or intravenously (10 ng/kg/min) with the brain unanesthetized.
Evoked reflex bradycardia using intravenous norepinephrine injections (2 µg/kg) and verified reflex integrity via atropine administration.
Intraventricular and intravertebral angiotensin II increased basal mean blood pressure by 16 mm Hg (p < 0.05), leaving norepinephrine-induced pressor responses and bradycardia unaffected.
Intravenous angiotensin II did not alter basal blood pressure but caused a 16 mm Hg increase (p < 0.05) in the norepinephrine pressor response without altering reflex bradycardia.
Atropine reversed norepinephrine-induced bradycardia and augmented pressor responses across all tested animals.

Structured PICO

Does central administration of angiotensin II alter norepinephrine-induced reflex bradycardia in cats?

Population

Cats (unanesthetized brain, spinal cats)

Intervention

Angiotensin II administered intravertebrally (10 ng/kg/min), into a lateral cerebroventricle (0.4 microgram/min), or intravenously (10 ng/kg/min)

Comparator

Baseline/control responses to norepinephrine (2 microgram/kg i.v.)

Outcome

Norepinephrine-induced reflex bradycardia and pressor responsessurrogate

Centrally administered angiotensin II does not alter the cardioinhibitory reflex to an acute pressor stimulus in cats.

Cite This Study

Severs et al. (2008) studied this question.

synapsesocial.com/papers/6a922dd33eb7c78f2e41d97f https://doi.org/10.1159/000136719

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Implication

Central angiotensin II raises basal BP without blunting reflex bradycardia in cats; hypothesis-generating for central RAS effects on human baroreflex.

Norepinephrine-Induced Reflex Bradycardia after Central Administration of Angiotensin II

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Norepinephrine-Induced Reflex Bradycardia after Central Administration of Angiotensin II

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider