What is the clinical evidence from this study?

Study design: Other. Intervention: Hypercapnia (end-expiratory CO2 from 5% to 10%) vs. Baseline. Primary outcome: Sympathetic nerve discharge (SND) and activity of RVLM neurons.

What question did this study set out to answer?

This study aims to understand how increased brain CO2 levels affect sympathetic nerve discharge and respiratory neuron activity.

August 11, 2006The Journal of PhysiologyOpen Access

Central chemoreceptors and sympathetic vasomotor outflow

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Key result

Hypercapnia increased sympathetic nerve discharge by 97 +/- 6% and the activity of RVLM neurons by 67 +/- 4% in anaesthetized rats.

Population

Anaesthetized sino-aortic denervated and vagotomized rats

Design

Preclinical

Authors

TMThiago S. MoreiraUniversidade de São Paulo ATAna C. TakakuraUniversidade de São Paulo ECEduardo ColombariFundação Faculdade de Odontologia

Discussion

Member takes

Implication

Should not yet change hypercapnia management in patients; extends evidence for RVLM chemoreceptor involvement in sympathoexcitation.

Key Points

This study aims to understand how increased brain CO2 levels affect sympathetic nerve discharge and respiratory neuron activity.
Recorded sympathetic nerve discharge, phrenic nerve discharge, and RVLM neuron activity in anesthetized rats.
Administered kynurenic acid and muscimol to evaluate their effects on neural responses to CO2 adjustments.
Performed experiments in sino-aortic denervated and vagotomized rat models.
Hypercapnia significantly increased sympathetic nerve discharge by 97 +/- 6% and RVLM neuron activity by 67 +/- 4%.
Kynurenic acid injections diminished phrenic nerve discharge but did not alter CO2 effects on sympathetic activity.
Muscimol injections into specific regions increased the stimulatory effect of CO2 on sympathetic nerve discharge.

Structured PICO

Population

Anaesthetized sino-aortic denervated and vagotomized rats.

Intervention

Hypercapnia (end-expiratory CO2 from 5% to 10%) and microinjections of kynurenic acid or muscimol into specific brain regions (RVLM, RTN, rVRG-pre-Bötzinger region, commNTS)

Outcome

Sympathetic nerve discharge (SND), phrenic nerve discharge (PND), and activity of RVLM neuronssurrogate

CO2 increases sympathetic nerve discharge by activating RVLM sympathoexcitatory neurons, with relevant central chemoreceptors likely located within or close to the RVLM.

Cite This Study

Moreira et al. (2006) studied this question. Hypercapnia (end-expiratory CO2 from 5% to 10%) vs. Baseline was evaluated on Sympathetic nerve discharge (SND) and activity of RVLM neurons. Hypercapnia increased sympathetic nerve discharge by 97 +/- 6% and the activity of RVLM neurons by 67 +/- 4% in anaesthetized rats.

synapsesocial.com/papers/6a71b64e6c240de38cdc3575 https://doi.org/10.1113/jphysiol.2006.115600

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Central chemoreceptors and sympathetic vasomotor outflow

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Central chemoreceptors and sympathetic vasomotor outflow

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider