ABSTRACT
Glutamine (Gln) is the most abundant a-amino acid in human plasma and muscle tissue. It is also the primary metabolic fuel for the small intestine. Gln has been traditionally viewed as nonessential, inasmuch as the glutamate contained in the diet or intravenous blood can be converted in the liver and skeletal muscle to Gln. Gln is currently available for oral and parenteral use. This chapter discusses the effect of the important amino acid on Na+ and fluid absorption; its impact on intestinal recovery from injury; and its unique signaling characteristics in the intestinal epithelium. Gln-mediated activation of the heat shock protein pathway is responsible for cellular protection which has been tested in fibroblasts and intestinal epithelial cells. Extracellular-signal-related kinase and phosphatidylinositol-3 kinase signaling pathways play critical roles in regulating the effects of Gln on intestinal cell growth and survival. Glutamine has been used in conjunction with growth hormone in patients with short bowel syndrome.
