Pharmacological Stress Thallium Scintigraphy With 2-Cyclohexylmethylidenehydrazinoadenosine (WRC-0470) A Novel, Short-Acting Adenosine A2A Receptor Agonist

Background Pharmacological stress imaging with adenosine or dipyridamole is associated with a high incidence of side effects, including hypotension, chest pain, AV conduction abnormalities, and bronchospasm. Although the desired coronary vasodilatory response is mediated primarily by the adenosine A2A receptors, these side effects result from stimulation of the A1, A2B, or A3 adenosine receptors. We hypothesized that a selective adenosine A2A receptor agonist would induce coronary vasodilatation appropriate for pharmacological stress imaging, without evoking adenosine receptor–mediated side effects. Methods and Results Infusions of a potent and selective A2A adenosine receptor agonist, WRC-0470 (0.1 to 3 μg · kg−1 ·min−1 for 10 minutes), to five open-chest dogs produced dose-related left anterior descending (LAD) and left circumflex (LCx) coronary artery vasodilatation without altering mean arterial pressure, heart rate, left atrial pressure, or left ventricular dP/dt. In the same dogs, adenosine (300 μg ...