What question did this study set out to answer?

To identify the autonomic and sensory nerve mechanisms responsible for heart rate changes following acute blood volume depletion in rats.

March 1, 1972Acta Physiologica Scandinavica

Circulatory Control via Vagal Afferents

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Population

Sprague-Dawley rats (and other rat strains)

Design

Preclinical

Authors

JCJan CastenforsStockholm South General Hospital TSTorgny SjöstrandKarolinska University Hospital

Discussion

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Implication

Rat vagal pathways for hemorrhage bradycardia leave open human translation; no basis yet for clinical practice changes.

Key Points

To identify the autonomic and sensory nerve mechanisms responsible for heart rate changes following acute blood volume depletion in rats.
Withdrew 20% to 35% of total blood volume in anesthetized Sprague-Dawley rats to induce acute hypovolemia.
Assessed cardiac responses following bilateral vagotomy, pharmacological blockade with atropine and propranolol, and carotid artery ligation.
Selectively transected communicating nerve branches between the superior and inferior laryngeal nerves to isolate afferent pathways.
Blood volume reduction consistently induced bradycardia, which was abolished by bilateral vagotomy, atropine administration, carotid artery ligation, or laryngeal communicating nerve exclusion.
Tachycardia was selectively blocked by propranolol, and combined administration of atropine and propranolol completely eliminated all heart rate changes during hemorrhage.
Afferent nerve fibers responsible for the bradycardic response travel primarily via the recurrent nerve and laryngeal communicans into the cranial portion of the cervical vagus.

Structured PICO

Population

Sprague-Dawley rats (and other rat strains)

Intervention

Withdrawal of 20-35% of blood volume (hemorrhage) with or without bilateral vagotomy, atropine, propranolol, or specific nerve/artery ligations

Outcome

Heart rate responsesurrogate

In rats, the heart rate response to hemorrhage is mediated by antagonistically acting receptor mechanisms, with bradycardia driven by vagal afferents running via the recurrent nerve and laryngeal communicans.

Cite This Study

Castenfors et al. (1972) studied this question.

synapsesocial.com/papers/6a855e0e2e6b8eab48d4c64e https://doi.org/10.1111/j.1748-1716.1972.tb05186.x

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Circulatory Control via Vagal Afferents

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Circulatory Control via Vagal Afferents

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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Also Consider