The anatomic and metabolic source of lactate in shock.

The size of the lactate pool in canine shock was measured directly by determining the lactate concentration of various organs. All organs tested, except skeletal muscle, had lactate concentrations similar to those of arterial blood. Skeletal muscles had much higher concentrations of lactate than did arterial blood. When 14C-labeled glucose was infused intravenously, it was concluded from the relative specific activities of glucose and lactate in blood that about one-third of lactic acid originates from blood glucose in shock. Only skeletal muscle had lower lactate specific activity than did blood. This is a possible indication that skeletal muscle is the site of production of lactate. Low glucose specific activity in muscle indicates massive glycogen breakdown, which probably serves as a metabolic precursor of lactate. Lactate production from amino acids produced by proteolysis could also play a role.