Adenine nucleotides play a central role in cellular processes involving the transduction of energy. Among striated muscles, the management of adenine nucleotide catabolism differs greatly. These differences can be understood by considering the distribution, activity, and kinetic characteristics of degradative enzymes. When these factors are weighed in light of the differing energetic demands faced by heart and skeletal muscle fiber types, a coherent picture emerges. Our analysis suggests that, as the routine energy demand of a particular muscle rises in relation to the tissue's capacity for oxidative metabolism, the pattern of adenine nucleotide degradation shifts toward increased rates of AMP deamination along with lessened rates of dephosphorylation.