Cardiac Adenosine Metabolism: Physiological Implications

Detailed knowledge of cardiac adenosine metabolism is highly desirable, because 1) adenosine is likely to be an important regulator of coronary flow, heart rate and contractility under pathophysiological conditions, 2) adenosine is a mediator of myocardial preconditioning, and 3) adenosine is used under clinical conditions to terminate tachyarrhythmias, to assess vascular flow reserve and to induce controlled systemic hypotension and platelet antiaggregation (1–4). However, due to the complexity of adenosine metabolism the integration of the different pathways into a comprehensive model may even confound experts. In the following, an attempt is made to structure our knowledge of cardiac adenine nucleoside metabolism, summarize details on the catalytic pathways and eventually develop a perspective on how one may attempt to assess global flux rates and the free cytosolic concentration of adenosine in alive cells and intact tissues.