title: Adenosine plasma level and A2A adenosine receptor expression: correlation with laboratory tests in patients with neurally mediated syncope.
abstract: OBJECTIVE
  The purpose of this study was to investigate the hypothesis that responses to the ATP test and head-up tilt test (HUT) may be correlated with different purinergic profiles.
  
  
  METHODS
  The ATP and HUT identify distinct subsets of patients with neurally mediated syncope (NMS). Adenosine and its A(2A) receptors (A(2A)R) may be implicated in the pathophysiology of NMS in patients with positive HUT. Nothing is known about the purinergic profile of patients with positive ATP.   PATIENTS AND MEASURES:  This prospective study includes a consecutive series of patients with suspected NMS. All patients underwent both HUT and ATP. Before testing, samples were collected for measurement of baseline adenosine plasma level (APL) and expression.
  
  
  RESULTS
  A total of 46 patients (25 men and 21 women) with a mean age of 57±18 years were enrolled. The HUT test was positive in 27 patients and the ATP test in 20. Both tests were positive in 9 and negative in 8. High APL was associated with high probability of positive HUT while low APL was associated with high probability of positive ATP. Expression of A(2A)R was lower in patients with positive ATP than in those with positive HUT.
  
  
  CONCLUSIONS
  These findings indicate that patients with NMS present different purinergic profiles and that responses to HUT and ATP are correlated with these profiles.
authors.affiliation: Department of Cardiology, CHU La Timone, 264, Rue Saint Pierre, 13005 Marseille, France. jean-claude.deharo@ap-hm.fr
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Deharo
authors.forename: Alexis
authors.initials: A
authors.lastname: Mechulan
authors.forename: Roch
authors.initials: R
authors.lastname: Giorgi
authors.forename: Frederic
authors.initials: F
authors.lastname: Franceschi
authors.forename: Sebastien
authors.initials: S
authors.lastname: Prevot
authors.forename: Eric
authors.initials: E
authors.lastname: Peyrouse
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Condo
authors.forename: Youlet
authors.initials: Y
authors.lastname: By
authors.forename: Jean
authors.initials: J
authors.lastname: Ruf
authors.forename: Michelino
authors.initials: M
authors.lastname: Brignole
authors.forename: Régis
authors.initials: R
authors.lastname: Guieu
mesh_terms: D000241:Adenosine / Q000097:blood*; D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004562:Electrocardiography; D006801:Humans; D008571:Men; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D043705:Receptor, Adenosine A2A / Q000235:genetics*; D012680:Sensitivity and Specificity; D019462:Syncope, Vasovagal / Q000097:blood* / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology; D018667:Tilt-Table Test; D014930:Women
chemical_list: D000889:Anti-Arrhythmia Agents; D015415:Biomarkers; D043705:Receptor, Adenosine A2A; D000241:Adenosine