Increased expression of adenosine A2A receptors in patients with spontaneous and head-up-tilt-induced syncope.
Heart Rhythm
; 4(7): 870-6, 2007 Jul.
Article
em En
| MEDLINE
| ID: mdl-17599669
ABSTRACT
BACKGROUND:
Adenosine may play a role in the triggering of neurocardiogenic syncope, but no information on adenosine receptors is available at the present time.OBJECTIVE:
The purpose of this study was to investigate whether adenosine A2A receptors expression is altered in patients with neurocardiogenic syncope.METHODS:
Adenosine plasma levels (APLs), the expression of A2A receptors, were measured (mean +/- standard error of the mean) during tilt testing. Expression of receptors was assessed on mononuclear cells using a selective receptor ligand.RESULTS:
At baseline, the APLs of 16 patients with a positive test were higher than those of 17 patients with a negative test and of those of a control group (2.10 +/- 0.30 vs. 0.40 +/- 0.05 and 0.41 +/- 0.06 muM, respectively; P <.0001). The number of receptors was higher in patients tested positive than in patients tested negative or in the control group (122 +/- 10 vs. 38 +/- 4 and 44 +/- 4 fmol/g of proteins, respectively; P <.0001). No difference was found in the affinity or synthesis among the three groups.CONCLUSION:
This study showed an increased number and an up-regulation of adenosine A2A receptors in patients with spontaneous syncope and a positive head-up tilt, which in the context of high APLs may play a role in the recurrence of syncopal episodes.
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Base de dados:
MEDLINE
Assunto principal:
Síncope
/
Regulação da Expressão Gênica
/
Receptor A2A de Adenosina
Tipo de estudo:
Observational_studies
Limite:
Adolescent
/
Adult
/
Aged
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article