Differences in Efficiency of Energy Transfer in Mitochondrial Systems Derived from Normal and Failing Hearts. ∗ †

Abstract

Summary and Conclusions

1. Oxidation rates employing a-ketoglutarate as substrate and efficiency of phosphorylation coupled with oxidation were studied in heart mitochondrial systems prepared from normal guinea pig hearts and hearts from guinea pigs in congestive heart failure. 2. O^N _O2 values were 1170 and 1032 for the normal guinea pig hearts and experimental guinea pig heart mitochondrial systems for α-ketoglutarate oxidation respectively. P/O ratios were 2.95 and 2.91 respectively. 3. Addition of cofactors (CoA, DPN and TPN), increased O^N _O2 values from 1170 to 1480 in the normal heart mitochondrial systems and from 1032 to 1524 in the mitochondrial systems derived from animals in experimental congestive heart failure. P/O ratios decreased slightly in the normal systems (2.95 and 2.32) while the P/O ratio decreased from 2.91 to 1.95 in the animals in congestive heart failure. 4. The increase in energy production parallels the overall increase in ∼ phosphorus during addition of cofactors in both normal animals and failure animals. Although the efficiency of phosphorylation in the mitochondrial system derived from failing hearts is markedly decreased during the influence of the cofactors, energy production is maintained by the inordinate increase in respiration. The possible relationship of this observation to basic physiologic mechanisms is suggested.