A2A adenosine receptor function in patients with vasovagal syncope

Area of Science:

• Cardiovascular Research
• Neuroscience
• Immunology

Background:

• Adenosine A2A receptors (A2AR) are implicated in vasovagal syncope (VVS) pathophysiology.
• Previous studies indicate high A2AR expression in VVS patients, but their functional significance remains unevaluated.

Purpose of the Study:

• To evaluate the functional characteristics of A2AR in VVS patients.
• To assess A2AR binding affinity and cAMP production in VVS patients compared to healthy controls.

Main Methods:

• Peripheral blood mononuclear cells from 16 VVS patients and 8 healthy controls were analyzed.
• Adonis, an A2AR agonist antibody, was used to determine dissociation constant (KD) and EC50 for cAMP production.
• A2AR expression levels were quantified.

Main Results:

• VVS patients exhibited higher A2AR expression compared to controls (11.5 ± 1.2 vs. 7.7 ± 0.8 AU, P = 0.04).
• A2AR binding affinity (KD) was lower in VVS patients (2.1 ± 0.02 × 10(-7) M) than in controls (5 ± 1 × 10(-8) M, P < 0.01).
• Despite lower affinity, A2AR function (cAMP production) was preserved in VVS patients, with comparable EC50 values to controls.

Conclusions:

• The functional capacity of A2AR in VVS patients is preserved, as evidenced by preserved cAMP production.
• Reduced A2AR affinity in VVS patients suggests altered receptor dynamics.
• These findings support the implication of A2AR in the physiopathology of vasovagal syncope.