States of myocardial metabolism related to ischemia

Energy metabolism of the heart in ischemia is mainly characterized by oxygen deficiency and lack of lactate removal. However, under certain circumstances substrate deficiency might contribute to disturbances of energy supply as well. Capillary permeability was determined from tracer washout kinetics of isolated hearts. Regulation of mitochondrial respiration was estimated from the relationship of phosphorylation potential vs. oxygen consumption. The results obtained suggest that at least under experimental conditions substrate supply at the level of capillary exchange can be a rate-limiting figure, as well as substrate supply at the mitochondrial level, i.e., NADH supply. The latter was inferred from the effects of cobalt and strontium ions on the regulation of respiration.