Model of coordinated nucleotide metabolism and nucleoside signaling in hypoxia and inflammation. In areas of ongoing inflammation, diminished oxygen supply coordinates the induction of CD39, CD73, and the adenosine A2B receptor. At such sites, activated neutrophils provide a readily available extracellular source of ATP, that through two enzymatic steps is converted to extracellular adenosine. Activation of surface adenosine receptors promotes a variety of protective physiologic responses (see text). Abbreviations: A, adenosine; AdoRA A2, adenosine receptor; AMP, adenosine monophosphate; ATP, adenosine triphosphate; cAMP, cyclic AMP.