Novel Mechanism of Action

Background. In patients with stable angina pectoris aminophylline, a nonselective antagonist of adenosine receptors, markedly improves exercise capacity. To establish the role played by A, adenosine receptors in the anti-ischemic action of aminophylline, the effects of bamiphylline, a selective A, antagonist, on exercise-induced ischemia were investigated in patients with stable angina pectoris. Methods and Results. In a single-blind, placebo-controlled, randomized cross-over trial in 18 patients, oral administration of 1200 mg bamiphylline increased both the time to 1-mm ST segment depression (from 524±+177 to 664±192 seconds, P<.01) and the rate-pressure product at 1-mm ST segment depression (from 159±31 to 190±34 beats per minute per mm Hg/104 (P<.001). End-diastolic and end-systolic left ventricular volumes, left ventricular ejection fraction, and systolic septal and posterior wall thickening investigated by two-dimensional echocardiography in 12 of the 18 patients were not affected by oral administration of bamiphylline (124±22 versus 125±20 mL, P=NS; 49±f12 versus 50±+13