Can lactate be used as a fuel by wounded tissue?

The role of lactate in the metabolism of the healing wound is poorly understood. The purpose of the present studies was to determine if despite a net lactate production, wounded (Wx) tissue could metabolize lactate and use it as an oxidative fuel. The extensor digitorum longus muscles (EDL) of weanling, male, Fischer rats were injured with lambda-carrageenan or injured thermally, and 5 and 3 days later, respectively, were incubated in a standard incubate that contained varying amounts of lactate (0 to 6 mmol/L added). Lactate uptake and oxidation, occurred in lambda-carrageenan Wx EDL, thermally injured EDL and non-Wx EDL in a dose-dependent manner. At lactate concentrations of less than 3 mmol/L in the incubate, there was net lactate production, but at lactate concentrations of 6 mmol/L there was no net lactate production by both Wx and non-Wx EDL. The increase in lactate oxidation was not associated with an alteration in the tissue content of adenosine triphosphate or creatine phosphate. It was associated with a reduction in glucose oxidation in Wx and non-Wx EDL and by a decrease in glucose uptake by Wx EDL. These data suggest that lactate may be used as an oxidative fuel by wounded tissue and in this regard may substitute for glucose.