Accelerated lung amino acid release in hyperdynamic septic surgical patients
D. A. Plumley, W. W. Souba, R. D. Hautamaki, T. D. Martin, T. C. Flynn, W. R. Rout and E. M. Copeland 3rd
Department of Surgery, University of Florida College of Medicine, Gainesville 32610.
Amino acid flux across the lungs was studied in humans to gain further
insight into the altered nitrogen metabolism that characterizes catabolic
disease states. Lung flux of glutamine, glutamate, and alanine was
determined in three groups of surgical patients with indwelling pulmonary
artery catheters: (1) preoperative controls (n = 14), (2) postoperative
elective general surgical patients (n = 10, and (3) hyperdynamic septic
surgical patients (n = 17). In controls the lung was an organ of amino acid
balance. These exchange rates did not change in general surgical patients.
In the septic group, glutamine release by the lung increased markedly from
a control value of 0.80 +/- 0.99 mumol/kg per minute to 6.80 +/- 1.32
mumol/kg per minute. This accelerated release rate was secondary to both an
increase in total pulmonary blood flow and an increase in the pulmonary
artery-systemic arterial concentration difference. The lung also became an
organ of significant alanine release in septic patients. The lung plays an
active metabolic role in the processing of amino acids and may be a key
regulator in interorgan nitrogen flux after major injury and infection.
