Objective: The role of A1 adenosine receptors in preconditioning in humans is unknown. To establish whether bamiphylline, a selective antagonist of A1 adenosine receptors, abolishes ischaemic preconditioning in man, 36 consecutive patients undergoing single-vessel coronary angioplasty were randomized to receive intravenous infusion of bamiphylline (5 mg.kg-1) or placebo (0.9% NaCl) immediately prior to the procedure.
Design: The mean values (+/- 1 SD) of ST segment shifts on the surface and intracoronary electrocardiograms were measured at the end of the first and second balloon inflations, both 2 min long. The severity of cardiac pain was obtained at the same time using a visual analogue scale.
Results: In bamiphylline-treated patients, the mean ST segment shift and the severity of cardiac pain during the second inflation were similar to those during the first inflation (14 +/- 15 vs 16 +/- 16 mm, ns and 31 +/- 28 vs 31 +/- 29, ns, respectively). Conversely, in placebo-treated patients both the mean ST segment shift and the severity of cardiac pain during the second inflation were significantly less than those during the first inflation (10 +/- 6 vs 17 +/- 7 mm, P < 0.001 and 25 +/- 21 vs 39 +/- 31 mm, P < 0.01, respectively). Thus, bamiphylline abolishes ischaemic preconditioning observed in man during repeated coronary balloon inflations.
Conclusion: These results suggest that, in this setting, ischaemic preconditioning is mediated, at least in part, by A1 adenosine receptors.