Dipyridamole has been proven to reduce targeting of Annexin A5 in responses to ischemic exercise, indicating protection against ischemia-reperfusion injury in humans (pharmacological preconditioning). Dipyridamole increases the endogenous adenosine level by inhibition of the nucleoside transporter (ENT-1). Activation of the adenosine receptor protects against ischemia-reperfusion injury. We hypothesize that endogenous adenosine mediates the protective effect of dipyridamole against ischemia-reperfusion injury. Therefore the adenosine receptor antagonist caffeine will reduce the benefit of dipyridamole on forearm ischemia-reperfusion injury.