Stabilization of a derangement in adenosine triphosphate metabolism during sustained, partial ischemia in the dog heart

Severe myocardial ischemia in dogs (perfusion 10% of normal) caused progressive deterioration in adenosine triphosphate (ATP) metabolism. Between ½ hour and 5 hours, myocardial ATP content fell from 55 to 6% of normal, and the sum of adenine nucleotides fell from 66 to 14% of normal. Moderate ischemia (perfusion 20 to 70%) also disturbed ATP metabolism, but to a lesser degree. Moreover, there was no significant change in the concentration of any ATP metabolite between Vi hour and 5 hours of moderate ischemia. ATP content was 66 and 52% of normal, and adenine nucleotide content was 73 and 59% of normal at ½ hour and 5 hours, respectively. Trivial ischemia (perfusion 80% or greater) barely perturbed ATP metabolism at either ½ hour or 5 hours. Thus, in contrast to severe or trivial ischemia, prolonged moderate ischemia produced a derangement in ATP metabolism that persisted and was relatively stable for 5 hours