Relationship of plasma amino acids to oxygen debt during hemorrhagic shock

Thirty dogs underwent hemorrhage over a 60 minute period to a predetermined O2 debt of 60-120 mL O2/kg, quantified real-time by a Beckman metabolic cart; they were then resuscitated with 120% of the shed volume. The [total amino acids], [lactate], and [alanine]/[glutamine] rose during hemorrhage and resuscitation. Blood pressure, VO2, cardiac index, circulating amino acid pool, and systemic amino acid transport decreased during hemorrhage, but rose during resuscitation. The [total amino acids], [alanine]/[glutamine], cardiac index, blood pressure, and [lactate] were significantly related to O2 debt. The O2 debt during hemorrhage was substantially better related to [lactate] compared to shed volume or blood pressure. The changes in [total amino acids] and [alanine]/[glutamine] and their relationship to O2 debt suggest a hemorrhagic-induced alteration in tissue amino acid kinetics. These data further suggest that using a metabolic substrate parameter such as O2 utilization is useful to stratify other cellular alterations such as amino acid uptake and release and lactic acidosis.