Glucose and fatty acid metabolism in the isolated working mouse heart

Although isolated perfused mouse heart models have been developed to study mechanical function, energy substrate metabolism has not been examined desp ite the expectation that the metabolic rate for a heart from a small mammal should be increased. Consequently, glucose utilization (glycolysis, oxidat ion) and fatty acid oxidation were measured in isolated working mouse heart s perfused with radiolabeled substrates, 11 mM glucose, and either 0.4 or 1 .2 mM palmitate. Heart rate, coronary flow, cardiac output, and cardiac pow er did not differ significantly between hearts perfused at 0.4 or 1.2 mM pa lmitate. Although the absolute values obtained for glycolysis and glucose o xidation and fatty acid oxidation are significantly higher than those repor ted for rat hearts, the pattern of substrate metabolism in mouse hearts is similar to that observed in hearts from larger mammals. The metabolism of m ouse hearts can be altered by fatty acid concentration in a manner similar to that observed in larger animals; increasing palmitate concentration alte red the balance of substrate metabolism to increase overall energy derived from fatty acids from 64 to 92%.