Glutamine Utilization by the Small Intestine

Windmueller, Herbert G.

doi:10.1002/9780470122983.ch6

Cited by 186 publications

(121 citation statements)

References 153 publications

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“…The enterocytes in the small intestine convert the most of Gln in diet and plasma to Ala, Cit and Pro that are released into the blood circulation in Gln-supplementation mammalian [9][10][11][12]. After entering the circulation, Cit is transported to the kidneys where it is converted to arginine (Arg) in human [129,130].…”

Section: Effects Of the Combination Of Ala Cit And Pro On • Oh-inducmentioning

confidence: 99%

“…The anti-oxidative and anti-apoptotic effects of Gln may be closely associated with its metabolites in mammalian. Studies showed that the small intestine converts the most of Gln in diet and plasma to alanine (Ala), citrulline (Cit) and Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/freeradbiomed proline (Pro), which released into the portal circulation in mammalian [9][10][11][12]. Ala exerts cytoprotection against oxidative stress in human endothelial cells [13] and rat hepatocytes [14].…”

Section: Introductionmentioning

confidence: 99%

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The metabolites of glutamine prevent hydroxyl radical-induced apoptosis through inhibiting mitochondria and calcium ion involved pathways in fish erythrocytes

Jiang

Liu

et al. 2016

Free Radical Biology and Medicine

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a b s t r a c tThe present study explored the apoptosis pathways in hydroxyl radicals ( • OH)-induced carp erythrocytes. Carp erythrocytes were treated with the caspase inhibitors in physiological carp saline (PCS) or Ca 2 þ -free PCS in the presence of 40 μM FeSO 4 /20 μM H 2 O 2 . The results showed that the generation of reactive oxygen species (ROS), the release of cytochrome c and DNA fragmentation were caspase-dependent, and Ca 2 þ was involved in calpain activation and phosphatidylserine (PS) exposure in • OH-induced carp erythrocytes. Moreover, the results suggested that caspases were involved in PS exposure, and Ca 2 þ was involved in DNA fragmentation in • OH-induced fish erythrocytes. These results demonstrated that there might be two apoptosis pathways in fish erythrocytes, one is the caspase and cytochrome c-dependent apoptosis that is similar to that in mammal nucleated cells, the other is the Ca 2 þ -involved apoptosis that was similar to that in mammal non-nucleated erythrocytes. So, fish erythrocytes may be used as a model for studying oxidative stress and apoptosis in mammal cells. Furthermore, the present study investigated the effects of glutamine (Gln)'s metabolites [alanine (Ala), citrulline (Cit), proline (Pro) and their combination (Ala 10 Pro 4 Cit 1 )] on the pathways of apoptosis in fish erythrocytes. The results displayed that Ala, Cit, Pro and Ala 10 Pro 4 Cit 1 effectively suppressed ROS generation, cytochrome c release, activation of caspase-3, caspase-8 and caspase-9 at the physiological concentrations, prevented Ca 2 þ influx, calpain activation, PS exposure, DNA fragmentation and the degradation of the cytoskeleton and oxidation of membrane and hemoglobin (Hb) and increased activity of anti-hydroxyl radical (AHR) in • OH-induced carp erythrocytes. Ala 10 Pro 4 Cit 1 produced a synergistic effect of inhibited oxidative stress and apoptosis in fish erythrocytes. These results demonstrated that Ala, Cit, Pro and their combination can protect mammal erythrocytes and nucleated cells against oxidative stress and apoptosis. The studies supported the use of Gln, Ala, Cit and Pro as oxidative stress and apoptosis inhibitors in mammal cells and the hypothesis that the inhibited effects of Gln on oxidative stress and apoptosis are at least partly dependent on that of its metabolites in mammalian.

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Section: Effects Of the Combination Of Ala Cit And Pro On • Oh-inducmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The metabolites of glutamine prevent hydroxyl radical-induced apoptosis through inhibiting mitochondria and calcium ion involved pathways in fish erythrocytes

Jiang

Liu

et al. 2016

Free Radical Biology and Medicine

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mentioning

confidence: 99%

“…In addition, glutamine is a major donor of carbon for gluconeogenesis (19). This explains why glutamine is extensively extracted in the splanchnic tissues in several animal species (39,47).In humans, the concomitant infusion of two tracers of glutamine (one infused intravenously, the other one enterally) can be used to assess the extraction of glutamine by the splanchnic bed. By using this technique, ϳ50 to 75% of enterally administered glutamine undergoes first-pass extraction within the splanchnic bed, presumably by the gut and liver, in healthy humans (4, 17, 18, 34).…”

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confidence: 99%

Corticosteroids increase glutamine utilization in human splanchnic bed

Thibault

Welch²,

Mauras³

et al. 2008

American Journal of Physiology-Gastrointestinal and Liver Physi

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Thibault R, Welch S, Mauras N, Sager B, Altomare A, Haymond M, Darmaun D. Corticosteroids increase glutamine utilization in human splanchnic bed. Am J Physiol Gastrointest Liver Physiol 294: G548-G553, 2008. First published December 27, 2007 doi:10.1152/ajpgi.00461.2007.-Glutamine is the most abundant amino acid in the body and is extensively taken up in gut and liver in healthy humans. To determine whether glucocorticosteroids alter splanchnic glutamine metabolism, the effect of prednisone was assessed in healthy volunteers using isotope tracer methods. Two groups of healthy adults received 5-h intravenous infusions of L-[1-14 C]leucine and L-[ 2 H5]glutamine, along with q. 20 min oral sips of tracer doses of L-[1-13 C]glutamine in the fasting state, either 1) at baseline (control group; n ϭ 6) or 2) after a 6-day course of 0.8 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 prednisone (prednisone group; n ϭ 8). Leucine and glutamine appearance rates (Ra) were determined from plasma [1-14 C]ketoisocaproate and [ 2 H5]glutamine, respectively, and leucine and glutamine oxidation from breath 14 CO2 and 13 CO2, respectively. Splanchnic glutamine extraction was estimated by the fraction of orally administered [ 13 C]glutamine that failed to appear into systemic blood. Prednisone treatment 1) did not affect leucine Ra or leucine oxidation; 2) increased plasma glutamine Ra, mostly owing to enhanced glutamine de novo synthesis (medians Ϯ interquartiles, 412 Ϯ 61 vs. 280 Ϯ 190 mol ⅐ kg Ϫ1 ⅐ h Ϫ1 , P ϭ 0.003); and 3) increased the fraction of orally administered glutamine undergoing extraction in the splanchnic territory (means Ϯ SE 64 Ϯ 6 vs. 42 Ϯ 12%, P Ͻ 0.05), without any change in the fraction of glutamine oxidized (means Ϯ SE, 75 Ϯ 4 vs. 77 Ϯ 4%, not significant). We conclude that high-dose glucocorticosteroids increase in splanchnic bed the glutamine requirements. The role of such changes in patients receiving chronic corticoid treatment for inflammatory diseases or suffering from severe illness remains to be determined. nutrition; protein metabolism; stable isotopes; stress; gut GLUTAMINE PLAYS AN IMPORTANT role in the maintenance of intestinal function (39,43,46). Glutamine indeed is both a preferred fuel (9, 47) for enterocytes and a precursor for the intestinal synthesis of purines, pyrimidines (9), and glutathione (37), and it may regulate gut protein synthesis (21,30,32). In addition, glutamine is a major donor of carbon for gluconeogenesis (19). This explains why glutamine is extensively extracted in the splanchnic tissues in several animal species (39,47).In humans, the concomitant infusion of two tracers of glutamine (one infused intravenously, the other one enterally) can be used to assess the extraction of glutamine by the splanchnic bed. By using this technique, ϳ50 to 75% of enterally administered glutamine undergoes first-pass extraction within the splanchnic bed, presumably by the gut and liver, in healthy humans (4, 17, 18, 34). Additionally, the major fate of splanchnic glutamine after enteral administration was oxidation, ...

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“…Hormônios como a insulina e os fatores de crescimento semelhantes à insulina (IGFs) estimulam o transporte de glutamina para o meio intracelular (18) , ao passo que glicocorticoides estimulam a liberação de glutamina para o meio extracelular (5,22) . Considerando-se que o gradiente transmembrana através da célula muscular é elevado para a glutamina, sua difusão livre através da membrana celular é restrita (23) .…”

Section: Considerações Metabólicas E Bioquímicas Da Glutaminaunclassified

Glutamina: aspectos bioquímicos, metabólicos, moleculares e suplementação

Cruzat

Petry

Tirapegui

2009

Rev Bras Med Esporte

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A glutamina é o aminoácido livre mais abundante no plasma e no tecido muscular. Nutricionalmente é classificada como um aminoácido não essencial, uma vez que pode ser sintetizada pelo organismo a partir de outros aminoácidos. A glutamina está envolvida em diferentes funções, tais como a proliferação e desenvolvimento de células, o balanço acidobásico, o transporte da amônia entre os tecidos, a doação de esqueletos de carbono para a gliconeogênese, a participação no sistema antioxidante e outras. Por meio de técnicas de biologia molecular, estudos demonstram que a glutamina pode também influenciar diversas vias de sinalização celular, em especial a expressão de proteínas de choque térmico (HSPs). As HSPs contribuem para a manutenção da homeostasia da célula na presença de agentes estressores, tais como as espécies reativas de oxigênio (ERO). Em situações de elevado catabolismo muscular, como após exercícios físicos intensos e prolongados, a concentração de glutamina pode tornar-se reduzida. A menor disponibilidade desse aminoácido pode diminuir a resistência da célula a lesões, levando a processos de apoptose celular. Por essas razões, a suplementação com L-glutamina, tanto na forma livre, quanto como dipeptídeo, tem sido investigada. Alguns aspectos bioquímicos, metabólicos e mecanismos moleculares da glutamina, bem como os efeitos de sua suplementação, são abordados no presente trabalho.Palavras-chave: glutamina, exercício, HSP, suplementação, dipeptídeo. aBStRaCtGlutamine is the most frequent free amino acid in the serum and muscular tissue. Nutritionally, it is classified as a non-essential amino acid, once it can be synthesized by the body from other amino acids. Glutamine is involved in different functions, such as cell proliferation and development, basic acid balance, ammonia transportation between tissues, carbon skeleton donation to the gluconeogenesis, participation in the antioxidant system, among others. Molecular biology techniques show that it may also influence several cell signaling ways, especially the expression of heat shock proteins (HSP). The HSPs contribute to the maintenance of the cellular homeostasis in the presence of stress agents such as oxygen reactive species (ORE). In situations of high cellular catabolism, as after intense and prolonged physical exercises, the glutamine concentration may become reduced. Lower availability of this amino acid may decrease the cell resistance to injuries, leading to cellular apoptosis processes. Therefore, L-glutamine supplementation either in free form or as dipeptide has been investigated. Some biochemical and metabolic aspects, molecular mechanism of glutamine, as well as the effects of its supplementation are approached in the present article.Keywords: glutamine, exercise, HSP, supplementation, dipeptide. intRodUÇÃoEm 1873, Hlasiwetz e Habermann foram os primeiros a considerar a glutamina como sendo uma molécula com propriedades biologicamente importantes. Posteriormente, novas observações levaram os pesquisadores a pensar que a amônia encontrada...

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Glutamine Utilization by the Small Intestine

Cited by 186 publications

References 153 publications

The metabolites of glutamine prevent hydroxyl radical-induced apoptosis through inhibiting mitochondria and calcium ion involved pathways in fish erythrocytes

The metabolites of glutamine prevent hydroxyl radical-induced apoptosis through inhibiting mitochondria and calcium ion involved pathways in fish erythrocytes

Corticosteroids increase glutamine utilization in human splanchnic bed

Glutamina: aspectos bioquímicos, metabólicos, moleculares e suplementação

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