AdenosinePerfusionReceptor, Adenosine A2AReceptor, Adenosine A1Adenosine DeaminaseReceptor, Adenosine A3Perfusion ImagingReceptor, Adenosine A2BAdenosine KinaseReceptors, Adenosine A2Adenosine A2 Receptor AgonistsAdenosine A2 Receptor AntagonistsReceptors, Purinergic P1Adenosine A1 Receptor AntagonistsMyocardial Perfusion ImagingAdenosine A1 Receptor AgonistsPurinergic P1 Receptor AntagonistsXanthinesPurinergic P1 Receptor AgonistsAdenosine MonophosphateAdenosine-5'-(N-ethylcarboxamide)TheophyllineCoronary CirculationReceptors, PurinergicAdenosine A3 Receptor AntagonistsTomography, Emission-Computed, Single-PhotonAdenosine A3 Receptor Agonists2-ChloroadenosinePhenethylaminesDipyridamoleInosinePhenylisopropyladenosineChemotherapy, Cancer, Regional Perfusion5'-NucleotidaseCyclic AMPRegional Blood FlowAdenosine TriphosphatasesCerebrovascular CirculationTubercidinAdenine NucleotidesHeartVasodilator Agents