Effect on myocardial metabolic pattern of local complete and incomplete ischemia.

After local complete ischemia at normothermia of 60, 100, 140, and 180 min duration the status of the adenylic acid-creatine phosphate system in the canine myocardium recovered to 98, 85, 74, and 30 percent of the control values, whereas glycogen was restored even more. In the infarcted myocardium the extent of alterations of the metabolic status was a function of the residual blood flow. Deviations from a regular metabolic status developed if the blood flow dropped below about 35 ml/min/100 gm. This critical flow rate is expected to vary with the energy requirement of the heart, but it is in keeping with results obtained by Rudolph and coworkers (personal communication) who found that patients with a myocardial blood flow below 30 ml/min/100 gm had a life expectancy of less than 1 month. In the nonaffected myocardium, both in experiments with local complete ischemia and in experiments with infarction, the metabolic status was always within normal ranges. This is in contrast to results published by Gudbjarnason (1971/1972) and Gudbjarnason, Puri, and Mathes (1971), who found that in noninfarcted myocardium tissue levels of ATP and creatine phosphate decreased to about 50 percent of the control values and that there was no restoration to normal values within 10 days after infarction.