Glutamine, the most abundant free amino acid in human plasma, has outstanding nutritional and non-nutritional properties. Glutamine regulates immune function and modulates cell metabolism. In particular, its administration showed a positive effect on glucose oxidation and on insulin resistance in different experimental and clinical studies. In humans, glutamine acts as both a substrate and modu...

Amino acids are required for activation of the mammalian target of rapamycin (mTOR) kinase which regulates protein translation, cell growth, and autophagy. Cell surface transporters that allow amino acids to enter the cell and signal to mTOR are unknown. We show that cellular uptake of L-glutamine and its subsequent rapid efflux in the presence of essential amino acids (EAA) is the rate-limitin...

Chinese Hamster Ovary (CHO) cells were propagated in vitro and exposed to varying doses of ionizing radiation. The surviving fraction of cells was determined, being found to be a function of the radiation dose. The cell survival curves obtained as a function of radiation dose were modified by the inclusion of varying doses of glutamine in the medium with glutamine demonstrating a radioprotectiv...

The effect of glutamine on the number of metacyclic trypanosomes produced in insect form cultures of Trypanosoma congolense TREU 1457 was investigated. When cultured in the absence of glutamine, trypanosomes did not develop to metacyclic forms. While metacyclics were produced in all cultures maintained with glutamine in the concentration range 2-20 mM, optimum numbers were obtained between 4 an...

Mycobacterium tuberculosis and other pathogenic mycobacteria export abundant quantities of proteins into their extracellular milieu when growing either axenically or within phagosomes of host cells. One major extracellular protein, the enzyme glutamine synthetase, is of particular interest because of its link to pathogenicity. Pathogenic mycobacteria, but not nonpathogenic mycobacteria, export ...

In order to study factors regulating renal ammoniagenesis, the transport and metabolism of L-glutamine were studied in mitochondria from kidneys of control and acidotic rats. On incubation in 1 mM [(14)C]glutamine, there was production and accumulation of [(14)C]glutamate within the matrix space. However no [(14)C]glutamine was detected in the matrix space, even with 10 mM [(14)C]glutamine as s...

Epileptic activity arises from an imbalance in excitatory and inhibitory synaptic transmission. To determine if alterations in the metabolism of glutamate, the primary excitatory neurotransmitter, might contribute to epilepsy we directly and indirectly modified levels of glutamine, an immediate precursor of synaptically released glutamate, in the rat neocortical undercut model of hyperexcitabil...

Oncogenes influence nutrient metabolism and nutrient dependence. The oncogene c-Myc stimulates glutamine metabolism and renders cells dependent on glutamine to sustain viability ("glutamine addiction"), suggesting that treatments targeting glutamine metabolism might selectively kill c-Myc-transformed tumor cells. However, many current or proposed cancer therapies interfere with the metabolism o...

An impairment of muscle glutamine metabolism in response to dexamethasone (DEX) occurs with aging. To better characterize this alteration, we have investigated muscle glutamine release with regard to muscle glutamine production (net protein breakdown, de novo glutamine synthesis) in adult and old glucocorticoid-treated rats. Male Sprague-Dawley rats (3 or 24 mo old) were divided into seven grou...

Glutamate-induced excitotoxicity has been proposed to mediate the death of retinal ganglion cells in glaucoma. The metabolic dependence of glutamatergic neurons upon glia via the glutamate/glutamine cycle to provide the precursor for neurotransmitter glutamate is well established. Thus, the aim of the present work was to study the retinal glutamate/glutamine activity in eyes with hypertension i...