Plasma glutamine

Glutamine, along with glucose, can stimulate insulin secretion by the endocrine pancreas. The significance of this is the regulation of the plasma glutamine concentration is not known. 

Figure 17.39 Effect of changes in glutamine levels in culture media on proliferation of human lymphocytes. The numbers represent the concentration of glutamine, in (xmol/L, in culture media. Note that both the maximum rate and the rate of response are decreased as the glutamine concentration in culture medium is decreased. The plasma glutamine level in normal humans is 600 (xmol/L.

Table 18.5 Plasma glutamine levels in normal subjects and patients...

Figure 21.25 Competition for plasma glutamine by immune and tumour cells. Glutamine is synthesised and released by muscle. However, if diet is supplemented with glutamine it is also released from the intestine.

Bachmann C, Colombo JP. Acid-base status and plasma glutamine in patients with hereditary urea cycle disorders. In Soeters PB, Wilson )HP, Meijer AJ, eds. Advances in ammonia metabolism and hepatic encephalopathy, 1st ed. Amsterdam Elsevier, 1988 72-8. 

In the first case of citrullinemia reported (M6), intermediary metabolites of the pyrimidine pathway were not sought in the urine. In the second, orotic acid was tested for, but not detected (M12). In the third child, orotic acid, uridine, and uracil were found in relatively large amounts in the urine when the plasma glutamine was at the very high level of 41.0 mg/100 ml, showing that in this genetic disorder, as in the other disorders of urea synthesis, these metabolites are always excreted in excess when the glutamine is raised (VI). 

Al-Hassnan ZN, et al. The relationship of plasma glutamine to ammonium and of glycine to add-base balance in propionic acidaemia. J Inherit Metab Dis. 2003 26(1) 89-91. 

Segal, S., and J. B. Wyngaarden. 1955. Plasma glutamine and oxypurine content in patients with gout. Proc. Soc. Exp. Biol. Med. 88 342. 

Glutamine deficiency occurs in critically ill patients, especially burn patients, as a result of increased protein turnover in the hypercatabolic state (56,57). Low levels of Glutamine on admission are associated with shock and increased hospital mortality and are more common in older persons (58). Glutamine supplementation in ICU patients was reviewed by the Italian Society of Enteral and Parenteral Nutrition (SINPE) (59), which noted that increased plasma glutamine levels were associated with improved outcomes in ICU patients. Other antioxidants such as parenteral selenium are also of interest in ICU patients (60). 

Oudemans-Van Straaten HM, Bosman RJ, Treskes M, et al. Plasma glutamine depletion and patient outcome in acute ICU admissions. Intensive Care Med 2001 27 84-90. 

Strenuous exerdse can cause significant immunosuppression along with a reduction in plasma glutamine levels. Following intense exerdse of greater than 1 h, lymphocyte coimt, natural killer cell activity, and lymphokine-activated killer cell activity were observed to decline." " Additionally, the lymphocyte proliferative response to T-cell mitogens decreased during exercise. Concomitant decline in... 

Hiscock, N. and Pedersen, B.K., Rxercise-induced immunodepression—plasma glutamine is not the link, J Appl Physiol, 93, 813, 2002. 

Hiscock, N., Mackinnon, L.T., A comparison of plasma glutamine concentration on athletes from different sports, Med Sci Sports Exerc, 30, 1693, 1998. 

Gleeson, M., Blannin, A.K., Walsh, N.P, Bishop, N.C., Clark, A.M., Effect of low-and high-carbohydrate diets on the plasma glutamine circulating leukocyte responses... 

Kargotich, S., Rowbottom, D., Keast, D., Goodman, C., Dawson, B., and Morton, A.R., Plasma glutamine changes after high-intensity exercise in elite male swimmers,... 

The maintenance of skeletal muscle and other body proteins is imder regulatory control by the interplay of various hormones and the availability of a variety of AAs. Whereas a transient sacrifice of body protein can benefit essential body functions dependent upon a steady supply of AAs, prolonged net loss of body protein eventually can compromise essential fimctions. The dispensability of skeletal protein has its limits, and a significant loss can soon impair work performance and other body functions. Consequently, body protein (especially skeletal muscle protein) can fimction to some extent as an AA reserve to meet a variety of functions throughout the body. One of these functions is the skeletal muscle maintenance of plasma glutamine levels to meet the needs of various cells, such as those of the gastrointestinal and immune systems (see Chapter 14). 

These brief reports have been confirmed by a more detailed description of a similar case (Truscott et al, 1979), a girl who died at 5 days of age with hyperammonaemia, and raised plasma glutamine, alanine and lysine. Increased excretion of 3-methylglutaric, 3-methylglutaconic and 3-hydroxy-3-methylglutaric acids (but not of 3-hydroxyisovaleric acid) was observed but at much lower concentrations than those in patients with authentic 3-hydroxy-3-methylglutaryl-CoA lyase deficiency, being 170,463 and 181 mmol mol of creatinine respectively or 20 per cent, 6 per cent and 1 per cent of the concentrations in an authentic patient. Measurement of enzyme activities in cultured fibroblasts showed these to be normal and a primary defect in the urea cycle was suspected ... 

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