What question did this study set out to answer?

To determine how the timing of intermittent chemical stimulation or depression of carotid body chemoreceptors relative to the respiratory cycle influences respiratory output.

April 1, 1972The Journal of PhysiologyOpen Access

The importance of timing on the respiratory effects of intermittent carotid body chemoreceptor stimulation

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Why the study?

Does the timing of intermittent carotid body chemoreceptor stimulation affect the respiratory response in anaesthetized cats?

Population

Anaesthetized cats

Comparison

Brief intermittent chemical stimulation or… vs Different timing of stimulation and bilateral…

Design

Preclinical

Authors

FEFrederic L. EldridgeUniversity of North Carolina at Chapel Hill

Discussion

Member takes

Implication

Phase-specific carotid body effects in anaesthetized cats are hypothesis-generating; human studies required before any clinical consideration.

Key Points

To determine how the timing of intermittent chemical stimulation or depression of carotid body chemoreceptors relative to the respiratory cycle influences respiratory output.
Monitored tidal volume and integrated peak phrenic activity in anesthetized cats receiving brief chemical stimulation or depression via NH4OH of the carotid body.
Used electrical recordings of carotid sinus nerve impulses to precisely time stimulus delivery during inspiration versus expiration, and verified responses following bilateral carotid body denervation.
Carotid body stimulation rapidly enhanced airflow, tidal volume, and phrenic discharge rate only when delivered during inspiration, with tidal volume increases confined to stimuli given in the last half of inspiration.
Stimulation during expiration caused a prolongation of expiration without altering subsequent breath volume, whereas late-inspiratory stimuli prolonged both inspiration and expiration.
Carotid body depression during inspiration reduced tidal volume and phrenic discharge, and bilateral denervation abolished all observed timing-dependent effects.

Structured PICO

Does the timing of intermittent carotid body chemoreceptor stimulation affect the respiratory response in anaesthetized cats?

Population

Anaesthetized cats

Intervention

Brief intermittent chemical stimulation or depression (by NH4OH) of the carotid body

Comparator

Different timing of stimulation (inspiration vs expiration) and bilateral carotid body denervation

Outcome

Respiratory response (tidal volume, integrated peak phrenic activity, air flow, phrenic discharge rate)surrogate

The respiratory response to carotid body stimulation is highly dependent on the timing within the respiratory cycle, with effects primarily seen during inspiration.

Cite This Study

Frederic L. Eldridge (1972) studied this question.

synapsesocial.com/papers/6a9650d7dbc641e6a0a6b3ec https://doi.org/10.1113/jphysiol.1972.sp009799

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Implication

Phase-specific carotid body effects in anaesthetized cats are hypothesis-generating; human studies required before any clinical consideration.