Glutamate metabolism in malnutrition and sepsis in man.

Abstract

The metabolism of intravenous glutamate has been studied for its usefulness as a nutrient in intravenous feeding regimens. Intravenously infused monosodium L-glutamate was rapidly removed from the blood with a half-life of 10.7 and 9.1 min in healthy control and malnourished septic patients, respectively. Under the same conditions, alanine was metabolized much more slowly, with a half-life of 35 min (1). After the infusion of glutamate, blood lactate fell and glucose was increased in the control patients but not in the sick patients. Blood pyruvate, ketone bodies, glutamine, aspartate and alanine levels did not change after the infusion of glutamate in either group of patients. Increased urinary excretion of aspartate was observed in the control patients following the infusion of glutamate, but in the sick patients there was an increased excretion of glutamine. Insulin concentration in the blood rose after the infusion of glutamate in the control patients but not in the sick patients. Although the glutamate half-life life was similar in the two groups of patients, glutamate was metabolized differently in the sick. Deamination predominates over transamination. We conclude that glutamate, in the amounts provided in intravenous feeding, is safe, although its effectiveness may be less than previously thought.