What is the clinical evidence from this study?

Study design: Other. Population: Normal cardiovascular physiology (animal model) (n=16). Intervention: Prolonged baroreflex activation (PBA) vs. Baseline (control period). Primary outcome: Mean arterial pressure and whole body plasma norepinephrine spillover (18 mmHg reduction in MAP and 45% decrease in NE spillover, p=<0.05).

What question did this study set out to answer?

The study aims to determine if there are compensatory adaptations that diminish the effects of sustained carotid sinus stimulation on sympathetic activity and blood pressure.

May 28, 2010AJP Heart and Circulatory PhysiologyOpen Access

Sustained suppression of sympathetic activity and arterial pressure during chronic activation of the carotid baroreflex

Q: What are the key findings of this study?

Prolonged baroreflex activation for 3 weeks produced a sustained 18 mmHg reduction in mean arterial pressure and a 45% decrease in plasma norepinephrine spillover without compensatory adaptations.

Q: What question did this study set out to answer?

The study aims to determine if there are compensatory adaptations that diminish the effects of sustained carotid sinus stimulation on sympathetic activity and blood pressure.

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Key result

Prolonged baroreflex activation for 3 weeks produced a sustained 18 mmHg reduction in mean arterial pressure and a 45% decrease in plasma norepinephrine spillover without compensatory adaptations.

Authors

TLThomas E. LohmeierJackson Memorial Hospital RIRadu IliescuGrigore T. Popa University of Medicine and Pharmacy TDTerry DwyerCommonwealth Scientific and Industrial Research Organisation

Discussion

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Implication

Baroreflex activation may sustain BP control without adaptation; leaves open translation to resistant hypertension in humans.

Key Points

The study aims to determine if there are compensatory adaptations that diminish the effects of sustained carotid sinus stimulation on sympathetic activity and blood pressure.
Measured whole body plasma norepinephrine spillover in six dogs over 3 weeks.
Assessed alpha(1)-adrenergic vascular reactivity during and after carotid baroreflex activation.
Monitored changes in mean arterial pressure and heart rate throughout the study.
Plasma norepinephrine spillover decreased by approximately 45% during the first week.
Mean arterial pressure and heart rate reduced by approximately 20 mmHg and 15 beats/min, respectively.
Sympathetic inhibition and blood pressure reduction effects were sustained with no compensatory increases in vascular reactivity.

PICO

Population

16 chronically instrumented mongrel dogs weighing 21-26 kg subjected to sinoaortic denervation or prolonged baroreflex activation for up to 3 weeks.

Intervention / Comparator

Prolonged baroreflex activation (PBA) vs Baseline (control period) (3-7 V, 30 Hz, 0.5-ms pulse duration)

Primary Outcome

Mean arterial pressure and whole body plasma norepinephrine spillover — 18 mmHg reduction in MAP and 45% decrease in NE spillover, p=<0.05

Main Result

Effect estimate: 18 mmHg reduction in MAP and 45% decrease in NE spillover

p-value: p=<0.05

Limitations

Animal model (dogs) which may not perfectly translate to human physiology
Did not assess whether there are changes in the responsiveness of alpha-2-adrenergic receptors during baroreflex activation

Cite This Study

Lohmeier et al. (2010) studied Normal cardiovascular physiology (animal model) (n=16). Prolonged baroreflex activation (PBA) vs. Baseline (control period) was evaluated on Mean arterial pressure and whole body plasma norepinephrine spillover (18 mmHg reduction in MAP and 45% decrease in NE spillover, p=<0.05). Prolonged baroreflex activation for 3 weeks produced a sustained 18 mmHg reduction in mean arterial pressure and a 45% decrease in plasma norepinephrine spillover without compensatory adaptations.

synapsesocial.com/papers/6a20dac76fcc58ca6c17fde4 https://doi.org/10.1152/ajpheart.00372.2010

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Sustained suppression of sympathetic activity and arterial pressure during chronic activation of the carotid baroreflex

Discussion

Member takes

Implication

Key Points

PICO

Main Result

Limitations

Cite This Study

Sustained suppression of sympathetic activity and arterial pressure during chronic activation of the carotid baroreflex

Discussion

Member takes

Implication

Key Points

PICO

Main Result

Limitations

Cite This Study

Also Consider

Also Consider