Turnover of amino acids in sepsis and starvation: Effect of glucose infusion

The catabolism of glucose and amino acids has been studied in the normal, the fasted, and the fasted septic dog. The fasted septic dog oxidized more glucose and alanine, and had more gluconeogenesis from alanine and the five tritiated amino acids--glutamate, threonine, phenylalanine, leucine, and valine--as compared to the normal and equally fasted dog. Thus the total body protein catabolic state was characterized in biochemical terms. In contrast, following glucose infusion, the fasted septic animal responded much like the fasted animal in terms of decreased animo acid gluconeogenesis and decreased plasma concentrations of amino acids, fats and fat products, but considerably increased the oxidation of alanine. The increased alanine oxidation appeared to be primarily related to increased tissue clearance and increased plasma concentration. There was some suggestive evidence for enhanced oxidation of the tritiated amino acids including leucine and valine during glucose infusion. The protein catabolic state secondary to this sort of sepsis in dogs only on per os fluid support appears to be best characterized as a glucose catabolic state with alanine being oxidized directly. Such states are known to be ones of enhanced metabolic rate secondary to enhanced synthetic processes generally. This is probably related to enhanced sympathetic nervous system release of glucagon with insulin being normally responsive to glucose because of a normal plasma epinephrine.