What question did this study set out to answer?

To determine whether pulmonary chemoreflex activation via pulmonary C-fiber stimulation produces reflex alterations in coronary vascular resistance.

September 1, 1985Circulation Research

Vagal chemoreflex coronary vasodilation evoked by stimulating pulmonary C-fibers in dogs.

Q: What is the clinical evidence from this study?

Study design: Other. Intervention: Stimulation of pulmonary C-fibers by right atrial injection of capsaicin. Primary outcome: Circumflex blood flow (p=<0.001).

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Key result

Stimulation of pulmonary C-fibers by right atrial injection of capsaicin increased circumflex blood flow by 32-109% (P<0.001), indicating reflex cholinergic vasodilation in the myocardium.

Population

Anesthetized, open-chest dogs

Comparison

Stimulation of pulmonary C-fibers by right… vs Left atrial injection of capsaicin and various…

Design

Preclinical

Authors

JCJ P ClozelRoche (Switzerland)ARAndrew M. RobertsUniversity of Louisville JHJulien I.E. HoffmanPediatric / Congenital Cardiology

Discussion

Member takes

Implication

Reflex coronary vasodilation occurs in canines; leaves open relevance to human coronary regulation or therapy.

Key Points

To determine whether pulmonary chemoreflex activation via pulmonary C-fiber stimulation produces reflex alterations in coronary vascular resistance.
Perfused the circumflex coronary artery at constant pressure (100 mm Hg) in anesthetized, open-chest dogs while recording circumflex blood flow.
Stimulated pulmonary C-fibers using right atrial capsaicin injections (10 µg/kg) during spontaneous rhythm and ventricular pacing, paired with vagal cooling (7–8°C vs. 0°C), vagotomy, and atropine administration.
Measured transmural myocardial blood flow distribution across different coronary perfusion pressures using the radioactive microsphere technique.
Right atrial capsaicin injection increased circumflex blood flow by 32–109% (P < 0.001) with spontaneous heart rate and by 26–100% (P < 0.001) under constant pacing, whereas left atrial injection had no effect.
Reflex coronary vasodilation was preserved during selective myelinated fiber blockade at 7–8°C, but was completely abolished by 0°C cooling, pulmonary vagal branch transection, or atropine.
Significant reflex vasodilation persisted even at lowered perfusion pressures without altering the transmural endocardial-to-epicardial blood flow ratio.

Structured PICO

Population

Anesthetized, open-chest dogs undergoing experiments to determine whether the pulmonary chemoreflex involves reflex changes in coronary vascular resistance.

Intervention

Stimulation of pulmonary C-fibers by right atrial injection of capsaicin (10 micrograms/kg)

Comparator

Left atrial injection of capsaicin (10 micrograms/kg) and various blockade conditions (cooling cervical vagus nerves, cutting pulmonary vagal branches, or giving atropine)

Outcome

Mean circumflex blood flow (coronary vasodilation)surrogate

Main Result

p-value: p=<0.001

Stimulation of pulmonary C-fibers triggers reflex cholinergic vasodilation in all layers of the myocardium in a canine model.

Cite This Study

Clozel et al. (1985) studied this question. Stimulation of pulmonary C-fibers by right atrial injection of capsaicin was evaluated on Circumflex blood flow (p=<0.001). Stimulation of pulmonary C-fibers by right atrial injection of capsaicin increased circumflex blood flow by 32-109% (P<0.001), indicating reflex cholinergic vasodilation in the myocardium.

synapsesocial.com/papers/6a9ebb08972e27e66c478b64 https://doi.org/10.1161/01.res.57.3.450

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Vagal chemoreflex coronary vasodilation evoked by stimulating pulmonary C-fibers in dogs.

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Cite This Study

Vagal chemoreflex coronary vasodilation evoked by stimulating pulmonary C-fibers in dogs.

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Cite This Study

Also Consider

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