A PROFILE OF AMINO-ACID AND CATECHOLAMINE LEVELS DURING ENDOTOXIN-INDUCED ACUTE LUNG INJURY IN SHEEP - SEARCHING FOR POTENTIAL MARKERS OF THE ACUTE RESPIRATORY-DISTRESS SYNDROME

The identification of plasma markers of the course of the acute respir atory distress syndrome (ARDS) is needed to improve its treatment and to further advance the development of new therapeutic agents. The stat us of markers of lung injury in ARDS is reviewed and some new potentia l markers are proposed. This study focused on plasma amino acids, rela ted amino compounds, and catecholamine levels during the acute phase o f endotoxin-induced lung injury in 8 sheep characterized by the onset of pulmonary edema caused by increased microvascular permeability. A n umber of significant changes from baseline values were found. During t he sixth hour of a 12-hour period of endotoxin infusion, norepinephrin e, epinephrine, and alanine levels increased whereas the isoleucine le vel decreased. During the sixth hour of the immediate postendotoxin pe riod, the taurine level increased while the levels of arginine, citrul line, glycine, isoleucine, methionine, ornithine, serine, threonine, a nd tryptophan decreased. These findings are compared with prior studie s in human subjects detailing the amino acid profile characteristic of advanced sepsis. We conclude that the present profile of catecholamin e and amino acid changes during endotoxemia in sheep deserves further study in human subjects to determine its significance as a marker of t he early stage of ARDS.