What question did this study set out to answer?

To examine whether and through which autonomic pathways carotid sinus baroreceptor stimulation decreases ventricular contractile force and heart rate.

March 1, 1965Acta Physiologica Scandinavica

Decrease in Cardiac Activity by Carotid Sinus Baroceptor Reflex

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Population

19 anesthetized cats

Comparison

Electrical stimulation of the sinus nerve or… vs Unstimulated state (baseline)

Design

Preclinical

Authors

PLPercy LindgrenSwedish Defence University JMJohn W. ManningUniversity of North Carolina at Chapel Hill

Discussion

Member takes

Implication

Animal data should not change practice; leaves open baroreflex effects on contractility in humans.

Key Points

To examine whether and through which autonomic pathways carotid sinus baroreceptor stimulation decreases ventricular contractile force and heart rate.
Assessed cardiac responses in 19 anesthetized, vagotomized cats following electrical stimulation of the sinus nerve or pressure elevation within the carotid sinus.
Maintained constant aortic pressure in select preparations to isolate primary inotropic and chronotropic responses from secondary hypotensive effects.
Evaluated the sympathetic mechanism by performing bilateral stellate ganglionectomy, administering 3–6 mg/kg of dichloroisoproterenol, and testing graded electrical stimulation of decentralized ganglia.
Baroreceptor excitation significantly decreased right ventricular contractile force, heart rate, and arterial blood pressure, persisting even when aortic pressure was artificially held constant.
Abolition of the inotropic and chronotropic reductions by stellate ganglionectomy and dichloroisoproterenol revealed that 40 per cent of baseline contractile force in vagotomized cats depends on tonic sympathetic activity.
Decentralized right stellate ganglion stimulation at 1/sec restored baseline rate and force, with 75 per cent of the maximum response achieved at 3/sec over an effective regulatory range of 40 mm Hg around normal blood pressure.

Structured PICO

Population

19 anesthetized cats

Intervention

Electrical stimulation of the sinus nerve or excitation of the carotid baroceptors by increasing the intrasinus pressure

Comparator

Unstimulated state (baseline)

Outcome

Right ventricular contractile force, heart rate, and blood pressuresurrogate

The sinus baroceptor reflex decreases cardiac contractility and heart rate via inhibition of sympathetic control, independent of hypotension.

Cite This Study

Lindgren et al. (1965) studied this question.

synapsesocial.com/papers/6a94027bb6c2e2f51e00deae https://doi.org/10.1111/j.1748-1716.1965.tb04080.x

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Decrease in Cardiac Activity by Carotid Sinus Baroceptor Reflex

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Decrease in Cardiac Activity by Carotid Sinus Baroceptor Reflex

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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Also Consider