Background: Adenosine is a nucleoside that impacts the cardiovascular system during cardiovascular or inflammatory diseases. The rapid determination of adenosine in blood may be useful in emergency medicine especially in syncope diagnose or septic shock. We compare its measurement in blood using fixed potential amperometry (FPA), with usual methods: mass spectrometry (LC-MS/MS) or high performance liquid chromatography (HPLC). Methods:Twenty healthy subjects (14 men and 6 women) and ten patients suffering from vasovagal syncope (VVS, 6 women and 4 men) were included. Blood samples were collected by vein puncture for plasma adenosine assay and in the same time using finger puncture for direct FAP measurement and on blotting paper for LC-MS/MS. Results:Mean plasma adenosine concentration was 26% higher using HPLC compared with LC-MSMS; p<0.01. In whole blood, adenosine concentration was 35% higher using FPA compared with LC-MS/MS. We found a good correlation between adenosine values measured by FAP and LC-MS/MS in whole blood and between LC-MS/MS and HPLC in plasma. Mean adenosine concentration was higher in patients whatever the method used. Conclusion:Adenosine measurement to the patient's bed, using FPA may be useful in some cases where high adenosine is associated with pejorative outcome.

Adenosine is an endogenous nucleoside which strongly impacts the cardiovascular system. Adenosine is released mostly by endothelial cells and myocytes during ischemia or hypoxia and greatly regulates the cardiovascular system via four specific G-protein-coupled receptors named A1R, A2AR, A2BR, and A3R. Among them, A2 subtypes are strongly expressed in coronary tissues, and their activation increases coronary blood flow via the production of cAMP in smooth muscle cells. A2A receptor modulators are an opportunity for intense research by the pharmaceutical industry to develop new cardiovascular therapies. Most innovative therapies are mediated by the modulation of adenosine release and/or the activation of the A2A receptor subtypes. This review aims to focus on the specific exploration of the adenosine plasma level and its relationship with the A2A receptor, which seems a promising biomarker for a diagnostic and/or a therapeutic tool for the screening and management of coronary artery disease. Finally, a recent class of selective adenosine receptor ligands has emerged, and A2A receptor agonists/antagonists are useful tools to improve the management of patients suffering from coronary artery disease.

The mechanism of atrial fibrillation (AF) in patients with normal heart remains unclear. While exogenous adenosine can trigger AF, nothing is known about the behavior of endogenous adenosine plasma level (APL) at the onset of AF and during ablation procedure. Ninety-one patients (68 with paroxysmal AF: 40 males, 66 ± 16 years; 23 with persistent AF: 14 males, 69 ± 11 years) and 18 controls were included. Among paroxysmal patients: i) medical therapy alone was performed in 45 cases and ablation procedure in 23. AF was spontaneously resolutive in 6 cases; ii) 23 underwent ablation procedure and blood was collected simultaneously in a brachial vein and in the left atrium; 17 were spontaneously in sinus rhythm while 6 were in sinus rhythm after direct current cardioversion. Among persistent patients: i) in 17 patients, blood samples were collected in a brachial vein before and after direct current cardioversion; ii) in 6 patients, blood samples were collected simultaneously in a brachial vein and in left atrium before and after cardioversion during ablation procedure. CV-APL was higher in patients with persistent AF vs patients with paroxysmal AF (median [