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de Souza DR, Vasconcelos DAAD, Murata GM, Fortes MAS, Marzuca-Nassr GN, Levada-Pires AC, Vitzel KF, Abreu P, Scervino MVM, Hirabara SM, Curi R, Pithon-Curi TC. Glutamine supplementation versus functional overload in extensor digitorum longus muscle hypertrophy. PHARMANUTRITION 2020. [DOI: 10.1016/j.phanu.2020.100236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Remesar X, Alemany M. Dietary Energy Partition: The Central Role of Glucose. Int J Mol Sci 2020; 21:E7729. [PMID: 33086579 PMCID: PMC7593952 DOI: 10.3390/ijms21207729] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/15/2020] [Accepted: 10/15/2020] [Indexed: 12/17/2022] Open
Abstract
Humans have developed effective survival mechanisms under conditions of nutrient (and energy) scarcity. Nevertheless, today, most humans face a quite different situation: excess of nutrients, especially those high in amino-nitrogen and energy (largely fat). The lack of mechanisms to prevent energy overload and the effective persistence of the mechanisms hoarding key nutrients such as amino acids has resulted in deep disorders of substrate handling. There is too often a massive untreatable accumulation of body fat in the presence of severe metabolic disorders of energy utilization and disposal, which become chronic and go much beyond the most obvious problems: diabetes, circulatory, renal and nervous disorders included loosely within the metabolic syndrome. We lack basic knowledge on diet nutrient dynamics at the tissue-cell metabolism level, and this adds to widely used medical procedures lacking sufficient scientific support, with limited or nil success. In the present longitudinal analysis of the fate of dietary nutrients, we have focused on glucose as an example of a largely unknown entity. Even most studies on hyper-energetic diets or their later consequences tend to ignore the critical role of carbohydrate (and nitrogen disposal) as (probably) the two main factors affecting the substrate partition and metabolism.
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Affiliation(s)
- Xavier Remesar
- Department of Biochemistry and Molecular Biomedicine Faculty of Biology, University Barcelona, 08028 Barcelona, Spain;
- IBUB Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain
- CIBER Obesity and Nutrition, Institute of Health Carlos III, 08028 Barcelona, Spain
| | - Marià Alemany
- Department of Biochemistry and Molecular Biomedicine Faculty of Biology, University Barcelona, 08028 Barcelona, Spain;
- IBUB Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain
- CIBER Obesity and Nutrition, Institute of Health Carlos III, 08028 Barcelona, Spain
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du Preez R, Wanyonyi S, Mouatt P, Panchal SK, Brown L. Saskatoon Berry Amelanchier alnifolia Regulates Glucose Metabolism and Improves Cardiovascular and Liver Signs of Diet-Induced Metabolic Syndrome in Rats. Nutrients 2020; 12:nu12040931. [PMID: 32230955 PMCID: PMC7231198 DOI: 10.3390/nu12040931] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 12/13/2022] Open
Abstract
Saskatoon berry (Amelanchier alnifolia) is a potential functional food containing anthocyanins and flavonols, as well as ellagitannins and phenolic acids. We have determined the potential therapeutic effects of Saskatoon berry in diet-induced metabolic syndrome. Nine- to ten-week-old male Wistar rats were randomly assigned to four groups. Two groups were fed on control diets, either corn starch (C) or high-carbohydrate, high-fat diet (H) respectively, for 16 weeks. Two further groups were fed on C or H diet for 16 weeks with Saskatoon berry powder added to the diet for the final 8 weeks (CSSK, HSSK). After 16 weeks, H rats showed symptoms of metabolic syndrome, including increased body weight, visceral adiposity, systolic blood pressure, cardiac fibrosis, plasma concentrations of triglycerides and non-esterified fatty acids, and plasma activities of alanine transaminase and aspartate transaminase. Saskatoon berry intervention normalised body weight and adiposity, improved glucose tolerance, decreased systolic blood pressure, improved heart and liver structure and function with decreased infiltration of inflammatory cells, and decreased plasma total cholesterol. Further, Saskatoon berry normalised liver expression of hexokinase 1 and glycogen phosphorylase and increased glucose 6-phosphatase relative to H rats. These results suggest that Saskatoon berry regulates glycolysis, gluconeogenesis and glycogenesis to improve metabolic syndrome.
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Affiliation(s)
- Ryan du Preez
- Functional Foods Research Group, University of Southern Queensland, Toowoomba, QLD 4350, Australia; (R.d.P.); (S.W.); (S.K.P.)
- School of Health and Wellbeing, University of Southern Queensland, Toowoomba, QLD 4350, Australia
| | - Stephen Wanyonyi
- Functional Foods Research Group, University of Southern Queensland, Toowoomba, QLD 4350, Australia; (R.d.P.); (S.W.); (S.K.P.)
| | - Peter Mouatt
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW 2480, Australia;
| | - Sunil K. Panchal
- Functional Foods Research Group, University of Southern Queensland, Toowoomba, QLD 4350, Australia; (R.d.P.); (S.W.); (S.K.P.)
| | - Lindsay Brown
- Functional Foods Research Group, University of Southern Queensland, Toowoomba, QLD 4350, Australia; (R.d.P.); (S.W.); (S.K.P.)
- School of Health and Wellbeing, University of Southern Queensland, Toowoomba, QLD 4350, Australia
- Correspondence: ; Tel.: +61-7-3812-6366
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de Vasconcelos DAA, Giesbertz P, de Souza DR, Vitzel KF, Abreu P, Marzuca-Nassr GN, Fortes MAS, Murata GM, Hirabara SM, Curi R, Daniel H, Pithon-Curi TC. Oral L-glutamine pretreatment attenuates skeletal muscle atrophy induced by 24-h fasting in mice. J Nutr Biochem 2019; 70:202-214. [DOI: 10.1016/j.jnutbio.2019.05.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 04/23/2019] [Accepted: 05/14/2019] [Indexed: 02/06/2023]
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5
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Some of the most interesting things we know, and don't know, about the biochemistry and physiology of elasmobranch fishes (sharks, skates and rays). Comp Biochem Physiol B Biochem Mol Biol 2016; 199:21-28. [DOI: 10.1016/j.cbpb.2016.03.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/28/2015] [Accepted: 03/07/2016] [Indexed: 11/21/2022]
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6
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Effects of dietary glutamine supplementation on the body composition and protein status of early-weaned mice inoculated with Mycobacterium bovis Bacillus Calmette-Guerin. Nutrients 2012; 3:792-804. [PMID: 22254124 PMCID: PMC3257735 DOI: 10.3390/nu3090792] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 08/16/2011] [Accepted: 08/23/2011] [Indexed: 11/19/2022] Open
Abstract
Glutamine, one of the most abundant amino acids found in maternal milk, favors protein anabolism. Early-weaned babies are deprived of this source of glutamine, in a period during which endogenous biosynthesis may be insufficient for tissue needs in states of metabolic stress, mainly during infections. The objective of this study was to verify the effects of dietary glutamine supplementation on the body composition and visceral protein status of early-weaned mice inoculated with Mycobacterium bovis Bacillus Calmette-Guérin (BCG). Mice were weaned early on their 14th day of life and seperated into two groups, one of which was fed a glutamine-free diet (n = 16) and the other a glutamine-supplemented diet (40 g/kg diet) (n = 16). At 21 days of age, some mice were intraperitoneally injected with BCG. Euthanasia was performed at the 28th day of age. BCG inoculation significantly reduced body weight (P < 0.001), lean mass (P = 0.002), water (P = 0.006), protein (P = 0.007) and lipid content (P = 0.001) in the carcass. Dietary glutamine supplementation resulted in a significant increase in serum IGF-1 (P = 0.019) and albumin (P = 0.025) concentration, muscle protein concentration (P = 0.035) and lipid content (P = 0.002) in the carcass. In conclusion, dietary glutamine supplementation had a positive influence on visceral protein status but did not affect body composition in early-weaned mice inoculated with BCG.
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7
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Importance of exercise immunology in health promotion. Amino Acids 2010; 41:1165-72. [PMID: 20976509 DOI: 10.1007/s00726-010-0786-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Accepted: 10/07/2010] [Indexed: 02/04/2023]
Abstract
Chronic physical exercise with adequate intensity and volume associated with sufficient recovery promotes adaptations in several physiological systems. While intense and exhaustive exercise is considered an important immunosuppressor agent and increases the incidence of upper respiratory tract infections (URTI), moderate regular exercise has been associated with significant disease protection and is a complementary treatment of many chronic diseases. The effects of chronic exercise occur because physical training can induce several physiological, biochemical and psychological adaptations. More recently, the effect of acute exercise and training on the immunological system has been discussed, and many studies suggest the importance of the immune system in prevention and partial recovery in pathophysiological situations. Currently, there are two important hypotheses that may explain the effects of exercise and training on the immune system. These hypotheses including (1) the effect of exercise upon hormones and cytokines (2) because exercise can modulate glutamine concentration. In this review, we discuss the hypothesis that exercise may modulate immune functions and the importance of exercise immunology in respect to chronic illnesses, chronic heart failure, malnutrition and inflammation.
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Rogero MM, Borelli P, Vinolo MAR, Fock RA, de Oliveira Pires IS, Tirapegui J. Dietary glutamine supplementation affects macrophage function, hematopoiesis and nutritional status in early weaned mice. Clin Nutr 2008; 27:386-97. [PMID: 18457905 DOI: 10.1016/j.clnu.2008.03.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 02/19/2008] [Accepted: 03/17/2008] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS To investigate the effect that early weaning associated with the ingestion of either a glutamine-free or supplemented diet has on the functioning of peritoneal macrophages, hematopoiesis and nutritional status of mice. METHODS Swiss Webster mice were early weaned on their 14th day of life and distributed to two groups, being fed either a glutamine-free diet (-GLN) or a glutamine-supplemented diet (+GLN). Animals belonging to a control group (CON) were weaned on their 21st day of life. RESULTS The -GLN and +GLN groups had a lower lean body mass, carcass protein and ash content, plasma glutamine concentration and lymphocyte counts both in the peripheral blood and bone marrow when compared to the CON group (P<0.05). Dietary supplementation with glutamine reversed both the lower concentrations of protein and DNA in the muscle and liver, as well as the reduced capacity of spreading and synthesizing nitric oxide, hydrogen peroxide, TNF-alpha, IL-1 beta and IL-6 in cultures of peritoneal macrophages obtained from the -GLN group (P<0.05). CONCLUSION These data indicate that the ingestion of glutamine modulates the function of peritoneal macrophages in early weaned mice. However, a glutamine-supplemented diet cannot substitute maternal milk in respect to immunological and metabolic parameters.
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Affiliation(s)
- Marcelo Macedo Rogero
- Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil.
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Diestel CF, Marques RG, Lopes-Paulo F, Paiva D, Horst NL, Caetano CER, Portela MC. Role of L-glutamine and glycine supplementation on irradiated colonic wall. Int J Colorectal Dis 2007; 22:1523-9. [PMID: 17690894 DOI: 10.1007/s00384-007-0341-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/14/2007] [Indexed: 02/04/2023]
Abstract
BACKGROUND AND AIMS Radiotherapy is frequently used for cancer treatment, but it may be associated with several complications. Thus, this study aimed to evaluate the role of L-glutamine and/or glycine supplementation on the colonic wall in rats submitted to abdominal radiation. MATERIALS AND METHODS Sixty adult Wistar rats were randomly divided into six groups: I-healthy, II (control)-irradiated rats without amino acid supplementation, III-irradiated rats with glycine supplementation, IV-irradiated rats with L-glutamine supplementation, V-irradiated rats with glycine supplementation 7 days before irradiation and with L-glutamine supplementation 7 days after irradiation, and VI-irradiated rats with L-glutamine supplementation 7 days before irradiation and with glycine supplementation 7 days after irradiation. Abdominal irradiation was employed with a dose of 1,000 cGy on the eighth day of the experiment. All animals underwent laparotomy on the 15th day for resection of a colonic segment for stereologic analysis. Parametric and nonparametric tests were used for statistical analysis, with the level of significance set at p<or=0.05. RESULTS Control animals (group II) presented a significantly smaller total volume of colonic wall when compared to animals of groups I, III, IV, V, and VI. There was a significant increase in mucosal layer volume in the animals of group IV compared to animals of groups I, II, and III. CONCLUSIONS Our findings suggest that L-glutamine and/or glycine supplementation is beneficial for the repair of the colonic wall of rats, but L-glutamine, with its trophic effects on the colonic mucosa, seems to exhibit better results.
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Affiliation(s)
- Cristina F Diestel
- Laboratory of Experimental Surgery, Department of General Surgery, Rio de Janeiro State University, Rio de Janeiro, Brazil
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Prentice AM, Rayco-Solon P, Moore SE. Insights from the developing world: thrifty genotypes and thrifty phenotypes. Proc Nutr Soc 2005; 64:153-61. [PMID: 15960860 DOI: 10.1079/pns2005421] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Few researchers would dispute that the pandemic of obesity is caused by a profound mismatch between humanity's present environmental circumstances and those that have moulded evolutionary selection. This concept was first articulated when gestational diabetes was described as being the result of a 'thrifty genotype rendered detrimental by progress'. More recently, this hypothesis has been extended to the concept of a 'thrifty phenotype' to describe the metabolic adaptations adopted as a survival strategy by a malnourished fetus; changes that may also be inappropriate to deal with a later life of affluence. Both the thrifty genotype and the thrifty phenotype hypotheses would predict that populations in some areas of the developing world would be at greater risk of obesity and its co-morbidities; a proposition to be explored in the present paper. To date thrifty genes remain little more than a nebulous concept propagated by the intuitive logic that man has been selected to survive episodic famine and seasonal hungry periods. Under such conditions those individuals who could lay down extra energy stores and use them most efficiently would have a survival advantage. The search for candidate thrifty genes needs to cover every aspect of human energy balance from food-seeking behaviour to the coupling efficiency of oxidative phosphorylation. The present paper will describe examples of attempts to find thrifty genes in three selected candidate areas: maternally-transmitted mitochondrial genes; the uncoupling proteins; apoE4, whose geographical distribution has been linked to a possible thrifty role in lipoprotein and cholesterol metabolism.
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Affiliation(s)
- Andrew M Prentice
- MRC International Nutrition Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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Macedo Rogero M, Tirapegui J, Pedrosa RG, Santana de Oliveira Pires I, Alves de Castro I. Plasma and tissue glutamine response to acute and chronic supplementation with L-glutamine and L-alanyl-L-glutamine in rats. Nutr Res 2004. [DOI: 10.1016/j.nutres.2003.11.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Cohen DM, Guthrie PH, Gao X, Sakai R, Taegtmeyer H. Glutamine cycling in isolated working rat heart. Am J Physiol Endocrinol Metab 2003; 285:E1312-6. [PMID: 12944323 DOI: 10.1152/ajpendo.00539.2002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To what extent does glutamine turnover keep pace with oxidative metabolism in the rat heart? To address this question, the following groups of substrates were presented to the isolated, working rat heart: 1) glucose (5 mM), insulin (40 microU/ml), and [2-13C]acetate (5 mM; high workload, n = 5); 2) pyruvate (2.5 mM) and [2-13C]acetate (5 mM; normal workload, n = 5); or 3) propionate (1 mM) and [2-13C]acetate (2.5 mM; normal workload, n = 3). In a subset of these experiments, the exchange of glutamate and glutamine was quantified by separation with ion exchange chromatography and analysis by GC-MS. There was an apparent equilibration of mass isotopomers of glutamate and glutamine after 50 min of perfusion, although the extent of equilibration was not determined. The fractional enrichment in glutamine was 31% of the enrichment of glutamate with the three different perfusates. From high-resolution nuclear magnetic resonance spectra, we found a ratio of glutamine to glutamate content of 94.1, 53.4, and 96.9%, respectively, for each experimental group. In experiments for which l-[1-13C]glutamine (5 mM) was included in the perfusate of group 2, [1-13C]glutamine was detected in the heart, but transfer of 13C from glutamine to glutamate was not detected (n = 4). We conclude that, in the perfused working heart, production of glutamine by amidation of glutamate takes place and can be detected, whereas the reverse process, generation of glutamate from glutamine, remains undetected.
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Affiliation(s)
- David M Cohen
- Department of Chemistry, University of Houston, Houston 77204, USA.
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Pereira LO, Francischi RPD, Lancha Jr. AH. Obesidade: hábitos nutricionais, sedentarismo e resistência à insulina. ACTA ACUST UNITED AC 2003. [DOI: 10.1590/s0004-27302003000200003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A obesidade já é considerada uma epidemia mundial independente de condições econômicas e sociais. O risco aumentado de mortalidade e morbidade associado à obesidade tem sido alvo de muitos estudos que tentam elucidar os aspectos da síndrome X como conseqüência da obesidade. Esta síndrome é caracterizada por algumas doenças metabólicas, como resistência à insulina, hipertensão, dislipidemia. Está bem estabelecido que fatores genéticos têm influência neste aumento dos casos de obesidade. No entanto, o aumento significativo nos casos de obesidade nos últimos 20 anos dificilmente poderia ser explicado por mudanças genéticas que tenham ocorrido neste espaço de tempo. Sendo assim, os principais fatores envolvidos no desenvolvimento da obesidade têm sido relacionados com fatores ambientais, como ingestão alimentar inadequada e redução no gasto calórico diário. Na tentativa de desencadear obesidade em animais e permitir o estudo desta doença de maneira mais completa, diversos modelos experimentais de obesidade têm sido desenvolvidos. Ainda que não possam ser considerados exatamente iguais aos modelos de obesidade humana, são de grande valor no estudo dos diversos aspectos que contribuem para este excessivo acúmulo de adiposidade e suas conseqüências.
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Swierczyński J, Bereznowski Z, Makarewicz W. Phosphate-dependent glutaminase of rat skeletal muscle. Some properties and possible role in glutamine metabolism. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1157:55-62. [PMID: 8499480 DOI: 10.1016/0304-4165(93)90078-m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A relatively high activity (26.7 nmol/min per mg mitochondrial protein) of phosphate-dependent glutaminase (EC 3.5.1.2; L-glutamine amidohydrolase) was found in rat skeletal muscle (mixed type from hindlegs) mitochondria incubated in 200 mM potassium phosphate (pH 8.2); the activity was lower in rat heart and diaphragm mitochondria. Phosphate-dependent glutaminase was also found in human skeletal muscle mitochondria, but the activity was about 3-5 times lower than in rat skeletal muscle. Multiplying the specific activity of mitochondrial glutaminase by the amount of mitochondrial protein present in 1 g of rat skeletal muscle the maximum glutaminase activity was found to be 0.352 mumol/min per g wet tissue. The rat skeletal muscle enzyme appears to be similar in many respects to phosphate-dependent glutaminase of the kidney (e.g., S0.5 for glutamine, K0.5 for phosphate, the pH activity profile, inhibition by glutamate). These properties make the skeletal muscle enzyme very similar to the 'kidney type' glutaminase isoenzyme of rat tissues. A significant difference between rat kidney and skeletal muscle enzymes is their adaptive response during acidosis. While the kidney enzyme increases during acidosis, the skeletal muscle glutaminase activity does not. A possible role of glutaminase in the glutamine metabolism in rat skeletal muscle is discussed.
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Affiliation(s)
- J Swierczyński
- Department of Biochemistry, Medical School of Gdańsk, Poland
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Hundal HS, Taylor PM, Willhoft NM, Mackenzie B, Low SY, Ward MR, Rennie MJ. A role for membrane transport in modulation of intramuscular free glutamine turnover in streptozotocin diabetic rats. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1180:137-46. [PMID: 1463765 DOI: 10.1016/0925-4439(92)90062-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We wished to examine the effects of diabetes on muscle glutamine kinetics. Accordingly, female Wistar rats (200 g) were made diabetic by a single injection of streptozotocin (85 mg/kg) and studied 4 days later; control rats received saline. In diabetic rats, glutamine concentration of gastrocnemius muscle was 33% less than in control rats: 2.60 +/- 0.06 mumol/g vs. 3.84 +/- 0.13 mumol/g (P < 0.001). In gastrocnemius muscle, glutamine synthetase activity (Vmax) was unaltered by diabetes (approx. 235 nmol/min per g) but glutaminase Vmax increased from 146 +/- 29 to 401 +/- 94 nmol/min per g; substrate Km values of neither enzyme were affected by diabetes. Net glutamine efflux (A-V concentration difference x blood flow) from hindlimbs of diabetic rats in vivo was greater than control values (-30.0 +/- 3.2 vs. -1.9 +/- 2.6 nmol/min per g (P < 0.001)) and hindlimb NH3 uptake was concomitantly greater (about 27 nmol/min per g). The glutamine transport capacity (Vmax) of the Na-dependent System Nm in perfused hindlimb muscle was 29% lower in diabetic rats than in controls (820 +/- 50 vs. 1160 +/- 80 nmol/min per g (P < 0.01)), but transporter Km was the same in both groups (9.2 +/- 0.5 mM). The difference between inward and net glutamine fluxes indicated that glutamine efflux in perfused hindlimbs was stimulated in diabetes at physiological perfusate glutamine (0.5 mM); ammonia (1 mM in perfusate) had little effect on net glutamine flux in control and diabetic muscles. Intramuscular Na+ was 26% greater in diabetic (13.2 mumol/g) than control muscle, but muscle K+ (100 mumol/g) was similar. The accelerated rate of glutamine release from skeletal muscle and the lower muscle free glutamine concentration observed in diabetes may result from a combination of: (i), a diminished Na+ electrochemical gradient (i.e., the net driving force for glutamine accrual in muscle falls); (ii), a faster turnover of glutamine in muscle and (iii), an increased Vmax/Km for sarcolemmal glutamine efflux.
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Affiliation(s)
- H S Hundal
- Department of Anatomy and Physiology, University of Dundee, UK
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Medina MA, Sánchez-Jiménez F, Márquez J, Rodríguez Quesada A, Núñez de Castro I. Relevance of glutamine metabolism to tumor cell growth. Mol Cell Biochem 1992; 113:1-15. [PMID: 1640933 DOI: 10.1007/bf00230880] [Citation(s) in RCA: 146] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- M A Medina
- Laboratorio de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Málaga, Spain
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Rennie MJ, Willhoft NM, Taylor PM. Glutamine transport and metabolism in mammalian skeletal muscle. Biochem J 1992; 285 ( Pt 1):339-40. [PMID: 1637318 PMCID: PMC1132786 DOI: 10.1042/bj2850339] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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