Substrate effects on mitochondrial function and tissue lipids in low-flow hypoxia of isolated perfused rat hearts.

A possible causal relationship between tissue FFA contents and the depression in mitochondrial oxidative phosphorylation in myocardial ischaemia has been suggested. To test this hypothesis, the effects of different substrates added to the perfusates of hypoxic, low-flow perfused hearts were examined on oxidative phosphorylation catalysed by mitochondria isolated from such tissue. In an additional series of experiments tissue neutral glyceride and FFA levels were analysed and correlated with changes in mitochondrial function. Mitochondria isolated from hearts with a high tissue FFA content exhibited the lowest ADP/O ratios, RCI and QO2 values. On the other hand, mitochondria isolated from hearts with reduced FFA contents, performed significantly better with respect to these parameters of mitochondrial function studied.