Since the first edition of this book considerable advances have been made on the metabolism of glutamine, justifying an entire symposium on the subject, with the proceedings appearing in 2001. A supplement on immunonutrition published in 2002 also addressed the role of glutamine. The compilation in Table 26.6 gives an insight into the diverse functions and biochemical linkages of glutamine. Although the bias is distinctly

Table 26.6. Glutamine metabolism: a summary of titles selected from the proceedings of two recent symposia.



Mechanisms governing the expression of the enzymes of glutamine

Labow et al. (2001)

metabolism - glutaminase and glutamine synthetase

Molecular advances in mammalian glutamine transport

Bode (2001)

Interaction between glutamine availability and metabolism of glycogen,

Rennie etal. (2001)

tricarboxylic acid cycle intermediates and glutathione

Role of mitochondrial glutaminase in rat renal glutamine metabolism

Curthoys (2001)

Glutamate—Y-aminobutyric acid-glutamine cycling in rodent and human

Behar and Roth man (2001)

cortex: the central role of glutamine

Glutamine and the bowel

Reeds and Burrin (2001)

Glutamine and cell signalling in liver

Haussinger etal. (2001)

Why is L-glutamine metabolism important to cells of the immune system

Newsholme (2001)

in health, postinjury, surgery or infection?

Glutamine in animal science and production

Lobley et al. (2001)

Glutamine and cancer

Medina (2001)

Assessment of safety of glutamine and other amino acids

Garlick (2001)

Glutamine alimentation in catabolic state

Boelens et al. (2001)

Glutamine in the fetus and low birth weight neonate

Neu (2001)

Glutamine: essential for immune nutrition in the critically ill

Andrews and Griffiths (2002)

Glutamine supplementation in bone marrow transplantation

Ziegler (2002)

Glutamine depletion impairs cellular stress response in human

Oehler et al. (2002)

leucocytes leucocytes towards clinical applications, there are implications for animal nutrition, health and welfare (Chapter 5; see also Lobley et ai, 2001).

It is widely acknowledged that gluta-mine is an important substrate, serving as a major respiratory fuel, glucogenic source and N carrier. Thus, in the synthesis of uric acid in poultry, glutamine is a key vehicle for the disposal and excretion of waste N. In addition, the glutamate-glutamine cycling in the central nervous system and the interorgan glucose-alanine-glutamine cycle are well-known features of amino acid metabolism. The role of glutamine in immune function is reviewed in a separate section below.

Wilmore and Rombeau (2001) suggest that several of the non-essential amino acids may become conditionally essential because endogenous synthesis cannot satisfy immediate requirements under conditions of stress. It is conceivable that factors such as disorders of pregnancy and lactation and bacterial and parasitic diseases may induce needs for amino acids such as glutamine, homocysteine and, in mammalian systems, arginine.

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