Effect of lactate and palmitate on substrate utilization of isolated rat soleus

The effects of exogenous lactate and palmitate on the metabolism of rat soleus muscle were studied. In the presence of glucose and insulin, the addition of 8 mM lactate resulted in a decrease in the oxidation of both glucose and other substrates. Lactate accounted for 70% of the oxygen consumption under these conditions. Glycogen accumulation and the incorporation of exogenous palmitate into triglycerides were stimulated by lactate addition, whereas the utilization of exogenous glycerol was depressed. The addition of 1 mM palmitate in either the presence or absence of lactate resulted in an inhibition of both glycolysis and the utilization of exogenous glucose. The results are discussed in terms of the effect of lactate levels on recovery from exercise.