Effects of selective carotid body stimulation with adenosine in conscious humans

Abstract

Stimulation of peripheral chemoreceptors by acute hypoxia causes an increase in minute ventilation (VI), heart rate (HR) and arterial blood pressure (BP). However, the contribution of particular chemosensory areas - carotid (CB) vs. aortic bodies - to this response in humans remains unknown. We performed a blinded, randomized and placebo controlled study in 11 conscious patients (9 men, 2 women) undergoing common carotid artery angiography. Doses of adenosine ranging from 4 to 512 μg or placebo solution of matching volume were administered in randomized order via a diagnostic catheter located in a common carotid artery. Separately, ventilatory and hemodynamic responses to systemic hypoxia were also assessed. Direct excitation of a CB with intra-arterial adenosine increased VI, systolic BP, mean BP and decreased HR. No responses in these variables were seen after injections of placebo. The magnitude of the ventilatory and hemodynamic responses depended on both the dose of adenosine used and on the level of chemosensitivity as determined by the ventilatory response to hypoxia. Percutaneous radio-frequency ablation of the CB abolished the adenosine evoked respiratory response and partially depressed the cardiovascular response in one participant. Our study confirms the excitatory role of purines in CB physiology in humans and suggests that adenosine may be used for selective stimulation and assessment of CB activity. The trial is registered at ClinicalTrials.gov NCT01939912.

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