Aminophylline inhibits adaptation to ischaemia during angioplasty Role of adenosine in ischaemic preconditioning

The ability of brief periods of ischaemia to protect the heartfrom subsequent ischaemia has been termed ‘ischaemic preconditioning’.In order to assess the role of adenosine receptor stimulationin this phenomenon we studied the ischaemic preconditioningeffect during angioplasty in 10 control patients and in 10 patientspre-treated with 5 mg kg^–1 aminophylline, an adenosinereceptor antagonist. The ischaemic response was assessed by analysis of the intracoronaryelectrocardiogram every 10 s during three consecutive inflationsof 90 s with a reperfusion time of 180 s. The severity of transmurallocal ischaemia was expressed as the magnitude of the ST segmentshift in relation to the time during each inflation. The controlpatients showed an improved tolerance to myocardial ischaemia:ST segment shift decreased from 1·42±0·49mV at the end of the first inflation to 1·03±0·44mV at the end of the third inflation (P<0·001). However,in patients pre-treated with aminophylline, the ischaemic responsewas not significantly different during three inflations. CONCLUSION: Aminophylline inhibits ischaemic preconditioning, as assessedby analysis of the intracoronary ST segment changes during angioplasty.This suggests that ischaemic preconditioning is mediated byadenosine receptor stimulation in humans.