Local effect of thermal injury on skeletal muscle blood flow and nucleotide levels.

We have previously shown that 3 days following a 3-sec scald of one hind limb, in vitro glucose utilization was markedly increased in soleus muscle from the burned limb but not in soleus from the contralateral unburned limb. The aim of the present study was to evaluate factors that might contribute to this local metabolic alteration. Three days following a 3-sec scald of one hind limb of the rat, blood flow through soleus and gastrocnemius muscles of the burned limb as measured with labeled microspheres was increased 167% (P less than 0.01) and 58% (P less than 0.04), respectively. Calf muscles of the burned limb, frozen in situ, showed a 48% decrease in ATP (P less than 0.001), 37% decrease in ADP (P less than 0.001), 192% increase in AMP (P less than 0.01), 45% decrease in total adenine nucleotides (P less than 0.001), 132% increase in pyruvate (P less than 0.001), and 377% increase in lactate (P less than 0.001). Blood flow and ATP, ADP, total nucleotides, and pyruvate levels of calf muscles of unburned limb of burned rats did not differ from controls, but AMP and lactate were increased 115% (P less than 0.05) and 144% (P less than 0.001), respectively. The decrease in ATP and increase in AMP and lactate in muscles of the burned limb suggest an increased rate of glycolysis in vivo which may be due, in part, to the stimulation of phosphofructokinase. Furthermore, the increased AMP and lactate may contribute to the increase in blood flow in muscles of the burned limb. It is proposed that thermal injury alters local adenine nucleotide levels, which results in elevated glucose utilization and blood flow in muscles of the burned region.