RESUMO
Magnesium (Mg2+) is an essential mineral for the functioning and maintenance of the body. Disturbances in Mg2+ intracellular homeostasis result in cell-membrane modification, an increase in oxidative stress, alteration in the proliferation mechanism, differentiation, and apoptosis. Mg2+ deficiency often results in inflammation, with activation of inflammatory pathways and increased production of proinflammatory cytokines by immune cells. Immune cells and others that make up the blood system are from hematopoietic tissue in the bone marrow. The hematopoietic tissue is a tissue with high indices of renovation, and Mg2+ has a pivotal role in the cell replication process, as well as DNA and RNA synthesis. However, the impact of the intra- and extracellular disturbance of Mg2+ homeostasis on the hematopoietic tissue is little explored. This review deals specifically with the physiological requirements of Mg2+ on hematopoiesis, showing various studies related to the physiological requirements and the effects of deficiency or excess of this mineral on the hematopoiesis regulation, as well as on the specific process of erythropoiesis, granulopoiesis, lymphopoiesis, and thrombopoiesis. The literature selected includes studies in vitro, in animal models, and in humans, giving details about the impact that alterations of Mg2+ homeostasis can have on hematopoietic cells and hematopoietic tissue.
Assuntos
Hematopoese , Células-Tronco Hematopoéticas , Deficiência de Magnésio , Magnésio , Animais , Diferenciação Celular , Linhagem Celular , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/efeitos dos fármacos , Homeostase , Humanos , Magnésio/farmacologia , Magnésio/fisiologiaRESUMO
Magnesium (Mg2+) is a mineral with the ability to influence cell proliferation and to modulate inflammatory/immune responses, due to its anti-inflammatory properties. In addition, mesenchymal stem cells (MSCs) modulate the function of all major immune cell populations. Knowing that, the current work aimed to investigate the effects of Mg2+ enrichment, and its influence on the immunomodulatory capacity of MSCs. Murine C3H/10T1/2 MSCs were cultivated in media with different concentrations of Mg2+ (0, 1, 3 and 5 mM), in order to evaluate the effects of Mg2+ on MSC immunomodulatory properties, cell proliferation rates, expression of NFκB and STAT-3, production of IL-1ß, IL-6, TGF-ß, IL-10, PGE2 and NO, and TRPM7 expression. The results showed that TRPM7 is expressed in MSCs, but Mg2+, in the way that cells were cultivated, did not affect TRPM7 expression. Additionally, there was no difference in the intracellular concentration of Mg2+. Mg2+, especially at 5 mM, raised proliferation rates of MSCs, and modulated immune responses by decreasing levels of IL-1ß and IL-6, and by increasing levels of IL-10 and PGE2 in cells stimulated with LPS or TNF-α. In addition, MSCs cultured in 5 mM Mg2+ expressed lower levels of pNFκB/NFκB and higher levels of pSTAT-3/STAT-3. Furthermore, conditioned media from MSCs reduced lymphocyte and macrophage proliferation, but Mg2+ did not affect this parameter. In addition, conditioned media from MSCs cultured at 5 mM of Mg2+ modulated the production profile of cytokines, especially of IL-1ß and IL-6 in macrophages. In conclusion, Mg2+ is able to modulate some immunoregulatory properties of MSCs.
Assuntos
Citocinas/metabolismo , Magnésio/fisiologia , Células-Tronco Mesenquimais/imunologia , Animais , Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Meios de Cultivo Condicionados/farmacologia , Citocinas/imunologia , Dinoprostona/metabolismo , Imunomodulação , Linfócitos/citologia , Linfócitos/efeitos dos fármacos , Macrófagos/citologia , Macrófagos/metabolismo , Magnésio/farmacologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Camundongos , NF-kappa B/metabolismo , Óxido Nítrico/metabolismo , Fator de Transcrição STAT3/metabolismo , Canais de Cátion TRPM/metabolismoRESUMO
Adipose tissue is considered an endocrine organ that promotes excessive production of reactive oxygen species when in excess, thus contributing to lipid peroxidation. Magnesium deficiency contributes to the development of oxidative stress in obese individuals, as this mineral plays a role as an antioxidant, participates as a cofactor of several enzymes, maintains cell membrane stability and mitigates the effects of oxidative stress. The objective of this review is to bring together updated information on the participation of magnesium in the oxidative stress present in obesity. We conducted a search of articles published in the PubMed, SciELO and LILACS databases, using the keywords 'magnesium', 'oxidative stress', 'malondialdehyde', 'superoxide dismutase', 'glutathione peroxidase', 'reactive oxygen species', 'inflammation' and 'obesity'. The studies show that obese subjects have low serum concentrations of magnesium, as well as high concentrations of oxidative stress marker in these individuals. Furthermore, it is evident that the adequate intake of magnesium contributes to its appropriate homeostasis in the body. Thus, this review of current research can help define the need for intervention with supplementation of this mineral for the prevention and treatment of disorders associated with this chronic disease.
Assuntos
Deficiência de Magnésio/fisiopatologia , Magnésio/fisiologia , Obesidade/fisiopatologia , Estresse Oxidativo/fisiologia , Suplementos Nutricionais , Humanos , Peroxidação de Lipídeos/efeitos dos fármacos , Magnésio/administração & dosagem , Magnésio/metabolismo , Deficiência de Magnésio/metabolismo , Deficiência de Magnésio/prevenção & controle , Malondialdeído/metabolismo , Modelos Biológicos , Obesidade/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismoRESUMO
OBJECTIVE: This review aims to bring updated information about the influence of magnesium deficiency on iron homeostasis and oxidative stress in type 2 diabetics. Data source: A bibliographic search was conducted in the databases Bireme, SciELO, Science Direct, PubMed and Portal.periodicos.Capes using the following descriptors: "diabetes mellitus", "magnesium", "iron", "oxidative stress" and "malondialdehyde". Fifty articles related to this literature were selected. Data synthesis: Several studies have shown the influence of hypomagnesemia on oxidative stress in type 2 diabetics. Deficiency of this mineral seems to be related to the induction of hemolysis, which favors the release of iron with overload of this mineral in the body, allowing an increase of the hydroxyl radical through the Fenton reaction and, consequently, oxidative stress. The increase in free iron contributes significantly to the manifestation of lipid peroxidation, which triggers a sequence of lesions in the cell with loss of selectivity in ion exchange and release of the contents of organelles, such as the hydrolytic enzymes of lysosomes, and the formation of cytotoxic products, such as malondialdehyde. CONCLUSIONS: There is scientific evidence that magnesium deficiency alters iron compartmentalization in the body; however, new studies are needed to bring information that would enable the biochemical understanding of the importance of the balance of magnesium and iron concentrations in protecting against the oxidative stress present in type 2 diabetes
OBJETIVO: Esta revisão visa trazer informações atualizadas sobre a influência da deficiência de magnésio na homeostase do ferro e estresse oxidativo em diabéticos tipo 2. Fonte de dados: O levantamento bibliográfico foi realizado nas bases de dados Bireme, Scielo, Science Direct, periódicos Capes e Pubmed com os seguintes descritores: "diabetes mellitus", "magnésio", "ferro", "estresse oxidativo" e "malondialdeído". Foram selecionados 50 artigos entre os relacionados por essa pesquisa bibliográfica. Síntese dos dados: Diversos estudos têm mostrado a influência da hipomagnesemia sobre o estresse oxidativo em diabéticos tipo 2, sendo que a deficiência desse mineral parece estar relacionada à indução da hemólise dos eritrócitos, que favorece a liberação do ferro com sobrecarga desse mineral no organismo, o que possibilita aumento do radical hidroxila por meio da reação de Fenton e, consequentemente, o estresse oxidativo. O aumento de ferro livre contribui de forma relevante para a manifestação da peroxidação lipídica, que desencadeia sequência de lesões na célula, com perda da seletividade na troca iônica e liberação do conteúdo de organelas, como as enzimas hidrolíticas dos lisossomas e a formação de produtos citotóxicos, como o malondialdeído. CONCLUSÕES: Há evidências científicas de que a deficiência de magnésio altera a compartimentalização do ferro no organismo, entretanto a realização de novos estudos é necessária para trazer informações que permitam o entendimento bioquímico da importância do equilíbrio das concentrações de magnésio e ferro na proteção contra o estresse oxidativo presente no diabetes tipo 2
Assuntos
Humanos , Masculino , Feminino , Diabetes Mellitus Tipo 2/metabolismo , Ferro/uso terapêutico , Magnésio/uso terapêutico , Estresse Oxidativo , Diabetes Mellitus Tipo 2/dietoterapia , Ferro/fisiologia , Magnésio/fisiologiaRESUMO
Minerals are essential nutrients for the body, are of inorganic nature which gives them the characteristic of being resistant to heat, are involved in a lot of chemical reactions in metabolism, regulating electrolyte balance, in maintaining bone, in the process of blood clotting and the transmission of nerve impulses, particularly its role as enzyme cofactors confers a key role in various physiological processes. Glucose homeostasis involves a fine coordination of events where hormonal control by insulin plays a key role. However, the role of minerals like magnesium, zinc, chromium, iron and selenium in the diabetes is less obvious and in some cases may be controversial. This review shows the knowledge of these five elements and their correlation with diabetes.
Los minerales son nutrientes esenciales para el organismo, de naturaleza inorgánica que les confiere, entre otras características, ser resistentes al calor, participan en diversas reacciones químicas del metabolismo en donde regulan el equilibrio hidroelectrolítico, el mantenimiento óseo, en la trasmisión de los impulsos nerviosos, y durante el proceso de coagulación sanguínea, particularmente por su función como cofactores enzimáticos, tienen un papel clave en varios procesos fisiológicos. La homeostasis de la glucosa involucra una fina coordinación de eventos en donde el control hormonal por la insulina tiene un papel primordial. Sin embargo, la función de los minerales, como el magnesio, el zinc, el cromo, el hierro y el selenio en la diabetes es menos evidente y puede ser, en algún caso, controversial. Esta revisión muestra el conocimiento acerca de estos cinco elementos y su correlación con la diabetes.
Assuntos
Diabetes Mellitus/metabolismo , Micronutrientes/fisiologia , Minerais/metabolismo , Animais , Cromo/deficiência , Cromo/fisiologia , Cromo/uso terapêutico , Diabetes Mellitus Experimental/metabolismo , Glucose/metabolismo , Homeostase , Humanos , Resistência à Insulina , Ferro/fisiologia , Ferro/uso terapêutico , Deficiências de Ferro , Magnésio/fisiologia , Magnésio/uso terapêutico , Deficiência de Magnésio/complicações , Deficiência de Magnésio/metabolismo , Síndrome Metabólica/metabolismo , Micronutrientes/uso terapêutico , Minerais/uso terapêutico , Estresse Oxidativo , Selênio/deficiência , Selênio/fisiologia , Selênio/uso terapêutico , Zinco/deficiência , Zinco/fisiologia , Zinco/uso terapêuticoRESUMO
The renin-angiotensin system is critically involved in regulating arterial blood pressure (BP). Inappropriate angiotensin type-1 receptor activation by angiotensin-II (Ang-II) is related to increased arterial BP. Mg has a role in BP; it can affect cardiac electrical activity, myocardial contractility, and vascular tone. To evaluate the relationship between high BP induced by a high sodium (Na) diet and Mg, and other mineral balances, two experimental rat models of salt-sensitive, induced-hypertension were used: Ang-II infused and Dahl salt-sensitive (SS) rats. We found that: 1) Ang-II infusion progressively increased BP, which was accompanied by hypomagnesuria and signs of secondary hyperaldosteronism; 2) an additive effect between Ang-II and a high Na load may have an effect on strontium (Sr), zinc (Zn) and copper (Cu) balances; 3) Dahl SS rats fed a high Na diet had a slow pressor response, accompanied by altered Mg, Na, potassium (K), and phosphate (P) balances; and 4) losartan prevented BP increases induced by Ang II-NaCl, but did not modify mineral balances. In Dahl SS rats, losartan attenuated high BP and ameliorated magnesemia, Na and K balances. Mg metabolism maybe considered a possible defect in this strain of rat that may contribute to hypertension.
Assuntos
Bloqueadores do Receptor Tipo 1 de Angiotensina II/uso terapêutico , Pressão Sanguínea/efeitos dos fármacos , Hipertensão/tratamento farmacológico , Losartan/uso terapêutico , Magnésio/fisiologia , Sistema Renina-Angiotensina/fisiologia , Angiotensina II/fisiologia , Angiotensina II/toxicidade , Animais , Pressão Sanguínea/fisiologia , Peso Corporal/efeitos dos fármacos , Diurese/efeitos dos fármacos , Ingestão de Líquidos/efeitos dos fármacos , Hiperaldosteronismo/etiologia , Hipertensão/etiologia , Hipertensão/genética , Hipertensão/fisiopatologia , Magnésio/sangue , Masculino , Minerais/sangue , Minerais/urina , Polidipsia/induzido quimicamente , Distribuição Aleatória , Ratos , Ratos Endogâmicos Dahl , Ratos Sprague-Dawley , Cloreto de Sódio na Dieta/efeitos adversosRESUMO
UNLABELLED: Magnesium (Mg++), Potassium (K+) and Calcium (CA++) are important electrolytes in keeping a stable electrical status. The purpose of this study was to measure them in critically ill patients. METHODS: We evaluated the electrolytes in 28 consecutive patients. Eighteen were females and 10 males with mean age of 62 +/- 5 years. RESULTS: The admission diagnosis in 95% of the cases was congestive heart failure. Sixty-four percent of the patients had subnormal values of Mg++, 53% subnormal values of K+, and 28% subnormal values of CA++. Fourteen percent showed lower values of the three electrolytes and 35% only of Mg++ and K+ concomitantly. Twenty-eight percent showed prolonged QTC interval. All patients with prolonged QTC interval had low Mg++ and K+ levels. Twenty five percent of the patients showed atrial fibrillation, 25% ventricular tachycardia, and 3% junctional tachycardia. The ventricular tachycardia group had more electrolyte abnormalities than those with atrial fibrillation. None of the patients received Mg++ replacement during critical management while 50% received K+ replacement. CONCLUSION: This data shows physician overlook the Importance of Mg++ and K+ deficiency in critically ill patients.
Assuntos
Desequilíbrio Ácido-Base/sangue , Estado Terminal , Cardiopatias/sangue , Magnésio/fisiologia , Desequilíbrio Ácido-Base/etiologia , Idoso , Cuidados Críticos/métodos , Complicações do Diabetes/sangue , Testes Diagnósticos de Rotina , Eletrocardiografia , Feminino , Cardiopatias/fisiopatologia , Humanos , Hipertensão/sangue , Hipopotassemia/sangue , Hipopotassemia/etiologia , Unidades de Terapia Intensiva , Magnésio/sangue , Masculino , Pessoa de Meia-Idade , Insuficiência Renal Crônica/sangueRESUMO
Requirements for optimal nutrition, especially for micronutrients, are not well defined for premature infants. The "reference fetus," developed by Ziegler et al,(1) has served as a model to define nutritional needs and studies designed to determine nutrient requirements. Revision of nutrient requirements and provision of optimal nutrition may lead to improved outcomes in preterm infants. Appropriate provision of nutrients also may help prevent nutritional disorders, such as metabolic bone disease and anemia. In this review, we discuss calcium, phosphorus, magnesium, vitamin D, iron, and copper, and define optimal intakes based on the available published data.
Assuntos
Fenômenos Fisiológicos da Nutrição do Lactente , Recém-Nascido Prematuro/fisiologia , Micronutrientes/fisiologia , Necessidades Nutricionais/fisiologia , Cálcio da Dieta/administração & dosagem , Cálcio da Dieta/metabolismo , Cobre/administração & dosagem , Cobre/fisiologia , Dieta , Suplementos Nutricionais , Humanos , Recém-Nascido , Ferro da Dieta/administração & dosagem , Ferro da Dieta/metabolismo , Magnésio/administração & dosagem , Magnésio/fisiologia , Micronutrientes/administração & dosagem , Fósforo na Dieta/administração & dosagem , Fósforo na Dieta/metabolismo , Vitamina D/administração & dosagem , Vitamina D/fisiologiaAssuntos
Diabetes Mellitus Tipo 2/metabolismo , Deficiência de Magnésio/complicações , Magnésio/fisiologia , Síndrome Metabólica/metabolismo , Animais , Glicemia/análise , Colesterol/metabolismo , Estudos de Coortes , Diabetes Mellitus Tipo 2/etiologia , Dieta , Feminino , Humanos , Hidroximetilglutaril-CoA Redutases/metabolismo , Hiperinsulinismo/urina , Hipertensão/metabolismo , Inflamação/metabolismo , Insulina/metabolismo , Resistência à Insulina/fisiologia , Transporte de Íons/fisiologia , Magnésio/urina , Deficiência de Magnésio/metabolismo , Masculino , Síndrome Metabólica/etiologia , Modelos Biológicos , Receptor de Insulina/metabolismoRESUMO
BACKGROUND: Magnesium modulates insulin-mediated glucose uptake but data regarding its role in insulin secretion are scarce; therefore, in this study we determined whether decreased serum magnesium levels are associated with the impairment of insulin secretion in non-diabetic individuals. METHODS: A total of 182 apparently healthy subjects, men and non-pregnant women, 18-65 years of age, were enrolled in a population-based cross-sectional study and allocated to groups with hypomagnesaemia and normomagnesaemia. The groups in the study were subsequently stratified according to glucose status: normal glucose tolerance, impaired fasting glucose, and impaired glucose tolerance. Insulin secretion was evaluated by the first and second phases of insulin secretion. RESULTS: The Spearman coefficient between serum magnesium and the first and second phases of insulin secretion showed a significant positive correlation in the overall (r = 0.265, p < 0.0005; r = 0.541, p < 0.0005), normal glucose tolerance (r = 0.369, p = 0.001; r = 0.618, p < 0.0005), impaired fasting glucose (r = 0.320, p = 0.02; r = 0.449, p = 0.001), and impaired glucose tolerance (r = 0.129, p = 0.37; r = 0.522, p < 0.0005) groups. The multivariate linear regression analysis showed a significant association between serum magnesium levels and the first and second phases of insulin secretion: for the entire groups [B = 75.2; 95% confidence interval (CI) 27.6-122.7; B = 25.4; 95% CI 16.4-34.3], normal glucose tolerance (B = 129.6, 95% CI 38.1-221.1; B = 40.3, 95% CI 23.7-56.8), impaired fasting glucose (B = 75.2, 95% CI 27.6-122.7; B = 15.1, 95% CI 4.2-30.2), and impaired glucose tolerance (B = 57.4, 95% CI 23.5-138.3; B = 25.4, 95% CI 16.4-34.3) groups. CONCLUSIONS: Our results show that hypomagnesaemia is associated with the decrease of the first and second phases of insulin secretion in non-diabetic subjects with hypomagnesaemia.
Assuntos
Insulina/metabolismo , Magnésio/sangue , Adolescente , Adulto , Idoso , Glicemia/metabolismo , Estudos Transversais , Jejum/metabolismo , Feminino , Intolerância à Glucose/metabolismo , Humanos , Resistência à Insulina/fisiologia , Secreção de Insulina , Magnésio/fisiologia , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND AND OBJECTIVES: Magnesium is predominantly an intracellular ion. Its blocking effects on NMDA receptors are responsible for the analgesic and sedative characteristics of this ion. The objective of this study was to review the physiology, pharmacology, and decreased plasma levels of magnesium, as well as its applications in obstetrics and anesthesia. CONTENTS: Magnesium is an intracellular cation with multiple functions: it is a cofactor for enzymes of the glucose metabolism and those that participate in the degradation of nucleic acids, proteins, and fatty acids; it regulates the movements of transmembrane ions; and it intervenes in the activity of several enzymes. Critical patients have a tendency to develop hypomagnesemia, and the treatment consists in correcting the cause, whenever possible, and replacement of magnesium. A reduction in the minimum alveolar concentration (MAC) of inhalational agents in animals and the use of opioids in humans under anesthesia has been demonstrated. CONCLUSIONS: Magnesium sulfate has been used in obstetrics with good results, inhibiting premature labor and in the treatment of eclampsia-associated seizures. It is potentially analgesic and sedative, and could be used as adjuvant during general anesthesia, attenuating the blood pressure response to tracheal intubation and decreasing the need of anesthetics.
Assuntos
Anestesia Obstétrica , Sulfato de Magnésio/uso terapêutico , Feminino , Humanos , Magnésio/fisiologia , Sulfato de Magnésio/farmacologia , GravidezRESUMO
Justificativa e objetivos: O magnésio é um íon predominantemente intracelular. Seu efeito bloqueador do receptor NMDA lhe confere características analgésicas e sedativas. O objetivo desse artigo foi revisar a fisiologia, a farmacologia e a diminuição da concentração plasmática do magnésio, assim como algumas das suas aplicações em obstetrícia e em anestesia. Conteúdo: O magnésio é um cátion intracelular que possui múltiplas funções: é cofator de enzimas do metabolismo glicídico e de enzimas da degradação dos ácidos nucleicos, proteínas e ácidos graxos; regula a passagem de íons transmembrana e intervém na atividade de várias enzimas. O paciente em estado crítico apresenta tendência à hipomagnesemia e o tratamento consiste em corrigir a causa quando possível acompanhada da reposição do magnésio. Já foi demonstrada a redução da concentração alveolar mínima (CAM) dos agentes inalatórios em animais e do uso de opioides em humanos sob anestesia. Conclusões: O sulfato de magnésio vem sendo utilizado em obstetrícia com boa efetividade para inibição do trabalho de parto prematuro e para o tratamento das crises convulsivas associadas ao quadro de eclâmpsia. É um fármaco com potencial analgésico e sedativo que pode ser utilizado como coadjuvante durante a anestesia geral atenuando a resposta pressórica à intubação traqueal e diminuindo a necessidade de anestésicos.
Background and objectives: Magnesium is predominantly an intracellular ion. Its blocking effects on NMDA receptors are responsible for the analgesic and sedative characteristics of this ion. The objective of this study was to review the physiology, pharmacology, and decreased plasma levels of magnesium, as well as its applications in obstetrics and anesthesia. Contents: Magnesium is an intracellular cation with multiple functions: it is a cofactor for enzymes of the glucose metabolism and those that participate in the degradation of nucleic acids, proteins, and fatty acids; it regulates the movements of transmembrane ions; and it intervenes in the activity of several enzymes. Critical patients have a tendency to develop hypomagnesemia, and the treatment consists in correcting the cause, whenever possible, and replacement of magnesium. A reduction in the minimum alveolar concentration (MAC) of inhalational agents in animals and the use of opioids in humans under anesthesia has been demonstrated. Conclusions: Magnesium sulfate has been used in obstetrics with good results, inhibiting premature labor and in the treatment of eclampsia-associated seizures. It is potentially analgesic and sedative, and could be used as adjuvant during general anesthesia, attenuating the blood pressure response to tracheal intubation and decreasing the need of anesthetics.
Justificativa y objetivos: El magnesio es un ión predominantemente intracelular. Su efecto bloqueador del receptor NMDA le confiere características analgésicas y sedativas. El objetivo de este artículo, fue revisar la fisiología, la farmacología y la disminución de la concentración plasmática del magnesio, como también de algunas de sus aplicaciones en obstetricia y en anestesia. Contenido: El magnesio es un catión intracelular que posee múltiples funciones: es cofactor de enzimas del metabolismo glicídico y de enzimas de la degradación de los ácidos nucleicos, proteínas y ácidos grasos; regula el paso de los iones transmembrana e interviene en la actividad de varias enzimas. El paciente en estado crítico, presenta una tendencia a la hipomagnesemia, y el tratamiento consiste en corregir la causa cuando es posible, acompañada de la reposición del magnesio. Ya ha quedado demostrada la reducción de la concentración alveolar mínima (CAM), de los agentes inhalatorios en animales y el uso de opioides en humanos bajo anestesia. Conclusiones: El sulfato de magnesio, ha venido siendo utilizado en obstetricia con una buena efectividad para la inhibición del parto prematuro y para el tratamiento de las crisis convulsivas asociadas al cuadro de eclampsia. Es un fármaco con potencial analgésico y sedativo que puede ser utilizado como coadyuvante durante la anestesia general, atenuando la respuesta presórica a la intubación traqueal y disminuyendo la necesidad del uso de anestésicos.
Assuntos
Feminino , Humanos , Gravidez , Anestesia Obstétrica , Sulfato de Magnésio/uso terapêutico , Sulfato de Magnésio/farmacologia , Magnésio/fisiologiaRESUMO
Este trabalho visa a contribuir com informações atualizadas sobre a relação entre exercício, estresse oxidativo e magnésio. São escassos os trabalhos que discutem a produção de radicais livres nesse contexto. A deficiência de magnésio altera a fluidez das membranas celulares e mitocondriais e promove perturbações na homeostase do cálcio e na atividade das defesas antioxidantes. No exercício, a falta de magnésio nos tecidos musculares os torna mais suscetíveis à infiltração de macrófagos e neutrófilos e ao rompimento do sarcolema, dificultando o processo de regeneração e podendo ocasionar queda no desempenho físico. Conclui-se que o papel metabólico da deficiência de magnésio no estresse oxidativo induzido pelo exercício deve ser mais pesquisado, focalizando os seus efeitos na musculatura esquelética em indivíduos que praticam exercício regular e na deficiência marginal de magnésio.
This article contributes to updated information about the relationship between exercise, oxidative stress and magnesium. There are few studies that discuss free radical production in this context. Magnesium deficiency alters cellular and mitochondrial membrane fluidity and promotes disturbances on calcium homeostasis and on the activity of antioxidant defenses. During exercise, lack of magnesium in muscle tissue turns them more susceptible to macrophage and neutrophil infiltration and to sarcolema damage, impairing the regeneration process and leading to decreased physical performance. In conclusion, the metabolic role of magnesium deficiency on exercise-induced oxidative stress should be further researched, focusing on its effects on skeletal muscle in individuals who practice regular physical exercise and in marginal magnesium deficiency.
Assuntos
Humanos , Deficiência de Magnésio/dietoterapia , Estresse Oxidativo/fisiologia , Exercício Físico/fisiologia , Magnésio/fisiologiaRESUMO
2-Cys peroxiredoxins (2-Cys Prx) are ubiquitous thiol-containing peroxidases that have been implicated in antioxidant defense and signal transduction. Although their biochemical features have been extensively studied, little is known about the mechanisms that link the redox activity and non-redox processes. Here we report that the concerted action of a nucleoside triphosphate and Mg(2+) on rapeseed 2-Cys Prx reversibly impairs the peroxidase activity and promotes the formation of high molecular mass species. Using protein intrinsic fluorescence in the analysis of site-directed mutants, we demonstrate that ATP quenches the emission intensity of Trp179, a residue close to the conserved Cys175. More importantly, we found that ATP facilitates the autophosphorylation of 2-Cys Prx when the protein is successively reduced with thiol-bearing compounds and oxidized with hydroperoxides or quinones. MS analyses reveal that 2-Cys Prx incorporates the phosphoryl group into the Cys175 residue yielding the sulfinic-phosphoryl [Prx-(Cys175)-SO(2)PO(3)(2-)] and the sulfonic-phosphoryl [Prx-(Cys175)-SO(3)PO(3)(2-)] anhydrides. Hence, the functional coupling between ATP and 2-Cys Prx gives novel insights into not only the removal of reactive oxygen species, but also mechanisms that link the energy status of the cell and the oxidation of cysteine residues.
Assuntos
Trifosfato de Adenosina/fisiologia , Brassica rapa/metabolismo , Cisteína/metabolismo , Peroxirredoxinas/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Brassica rapa/genética , Humanos , Magnésio/fisiologia , Dados de Sequência Molecular , Peroxirredoxinas/genética , Fosforilação , Proteínas de Plantas/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
The present work provides information about magnesium (Mg) physiology, Mg supplementation during normal pregnancy, and the use of Magnesium Sulfate MgSO4 in preeclampsia and eclampsia. Intestinal absorption, renal excretion and cellular distribution of Mg are described. In addition, this review includes several functions in which Mg is involved such as bone structure, enzymatical activities, cellular signaling, ionic channel regulation and gene expression. Furthermore, Mg supplementation for the prevention of preterm delivery, low birth weight, and preeclampsia are discussed. Results about the use of MgSO4 as treatment of preeclampsia and eclampsia are also revised. Finally, the effects of Mg upon the synthesis, secretion and/or action of vasoactive factors involved in blood pressure and uteroplacental flux regulation are described.
Assuntos
Magnésio/fisiologia , Pré-Eclâmpsia/etiologia , Feminino , Humanos , Magnésio/metabolismo , Magnésio/uso terapêutico , Pré-Eclâmpsia/prevenção & controle , GravidezRESUMO
OBJECTIVE: To study the role of magnesium in the endothelial dysfunction of canine coronary arteries caused by cardiopulmonary bypass (CPB) global ischemia followed by reperfusion. DESIGN: Segments of canine coronary arteries were suspended in organ chambers to measure isometric contraction by prostaglandin F (2alpha), and relaxed by acetylcholine (ACh), sodium fluoride (NaF), calcium ionophore (A23187) and sodium nitroprusside (SNP) in crescent concentrations. The investigation protocol had groups with six dogs: CONTROL group (without CPB), CPB group (105 min of CPB without aortic cross-clamping), ISCH group (45 min of CPB with aortic cross-clamping), ISCH/REP group (45 min of aortic cross-clamping followed by 60 min of reperfusion). The coronary relaxations were evaluated with (phase I), without (phase II) and restored magnesium (phase III) to the organ bath. RESULTS: The presence of magnesium in the organ bath was associated with the greater relaxation in response to agonists of the nitric oxide production. The removal of magnesium from the organ bath was associated with the reduction in the intensity of vessel relaxation. The magnesium restoration to the organ bath was associated with the additional reduction in the intensity of relaxation with the exception of NaF that allowed re-acquisition of the relaxation observed in the presence of magnesium. CONCLUSION: This in vitro study demonstrates that magnesium ion favorably influences the nitric oxide production by the coronary endothelium, attenuating the endothelial dysfunction caused by global ischemia followed by reperfusion.
Assuntos
Vasos Coronários/metabolismo , Endotélio Vascular/fisiopatologia , Magnésio/fisiologia , Vasodilatação/fisiologia , Acetilcolina/farmacologia , Animais , Calcimicina/farmacologia , Ponte Cardiopulmonar , Dinoprosta/farmacologia , Cães , Relação Dose-Resposta a Droga , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Proteínas de Ligação ao GTP , Técnicas In Vitro , Magnésio/uso terapêutico , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Reperfusão Miocárdica , Óxido Nítrico/biossíntese , Nitroprussiato/farmacologia , Transdução de Sinais/fisiologia , Fluoreto de Sódio/farmacologiaRESUMO
BACKGROUND: Cyclosporin A (CsA) nephrotoxicity has been attributed primarily to renal haemodynamic alterations caused by afferent arteriolar vasoconstriction. However, CsA nephropathy is also characterized by CsA-induced pre-glomerular disturbances and interstitial injury that may occur independently of haemodynamic changes. Given the high lipophilic activity of CsA, we hypothesized that direct tubular injury is likely to contribute to nephrotoxicity. METHODS: To investigate tubular toxicity of CsA, increasing concentrations of CsA (1, 2.5, 10, 25, 50 and 100 micro g/ml) and its vehicle (cremophor) were added to isolated rat proximal tubules (PT). Cell injury was assessed by lactate dehydrogenase (LDH) release. The role of Ca(2+) ions in tubular toxicity and the effect of calcium channel blockers on CsA toxicity were evaluated by measuring intracellular calcium using the fluorescent dye Fura-2 AM. The role of Mg(2+) ions was assessed using high extracellular Mg(2+) medium (2 mM). RESULTS: Whereas cremophor alone was not toxic to PT, CsA caused PT injury but only at the highest concentration (100 micro g/ml). After 90 min incubation, LDH was 22.5% in control PT and 41.9% in PT treated with 100 micro g/ml CsA (P < 0.001, n = 11). There was a transient increase in intracellular calcium ([Ca(2+)](i)) after CsA administration. A low calcium medium (100 nM) prevented CsA injury to renal tubules. However, verapamil, but not nifedipine, enhanced cell damage. Only nifedipine completely prevented [Ca(2+)](i) increases following CsA. Finally, a high Mg(2+) medium attenuated CsA-induced injury. CONCLUSION: We found that high CsA concentrations caused Ca(2+)- and Mg(2+)-dependent PT injury. Thus, low extracellular Ca(2+) and high Mg(2+) media attenuated CsA-induced tubular injury. Verapamil, but not nifedipine, enhanced CsA tubular toxicity. Therefore, CsA-induced tubular injury may contribute to CsA nephrotoxicity independently of haemodynamic disturbances.
Assuntos
Cálcio/fisiologia , Ciclosporina/efeitos adversos , Imunossupressores/efeitos adversos , Túbulos Renais Proximais/efeitos dos fármacos , Magnésio/fisiologia , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Cátions Bivalentes , Técnicas de Cultura , Túbulos Renais Proximais/patologia , Masculino , Ratos , Ratos Wistar , Equilíbrio Hidroeletrolítico/efeitos dos fármacos , Equilíbrio Hidroeletrolítico/fisiologiaRESUMO
During the last few years, magnesium (Mg) has been subject of research due to its functionality in the organism. It is one of the most important micronutrients, and therefore its role in biological systems has been extensively investigated. Particularly, Mg has a strong relation with the immune system, in both nonspecific and specific immune response, also known as innate and acquired immune response. The aim of this paper is to review the state of the art about the interactions between Mg and the immune system. We discuss the link between dietary Mg and inflammation, apoptosis and alterations in number and function of innate immune cell populations, described in animal models. Furthermore, the immune system can be compromised in human populations under certain circumstances, including athletes and elderly people. The importance of a balanced Mg homeostasis and its interaction with the immune system in these groups has also been reviewed. Although emerging data support the relevant role of Mg in the immune response, further research is needed; and special efforts should be made to establish the most adequate dose in nutritional supplements to reach beneficial effects on health.
Assuntos
Sistema Imunitário/fisiologia , Magnésio/fisiologia , Envelhecimento/imunologia , Envelhecimento/fisiologia , Animais , Apoptose/imunologia , Asma/imunologia , Modelos Animais de Doenças , Humanos , Imunidade Inata , Inflamação/imunologia , Necessidades NutricionaisRESUMO
In the present work, a Mg(2+)-dependent, Ca(2+)-stimulated ATPase activity was determined and characterized in purified preparations of syncytiotrophoblast basal (fetal facing) plasma membranes, and its characteristics were compared to those of the active Ca(2+)-transport already demonstrated in this tissue. Similar to the active Ca(2+)transport, the Ca-ATPase is Mg(2+)-dependent, is stimulated by calmodulin, and is inhibited by vanadate. The K(m) for Ca(2+)activation is 0.25+/- 0.02microM, a value near to that described for calcium active transport in this tissue. Consequently, the Ca-ATPase activity of human syncytiotrophoblast basal plasma membrane described in this paper could be responsible for the active extrusion of calcium from the syncytiotrophoblast toward the fetal circulation.
Assuntos
Membrana Basal/enzimologia , ATPases Transportadoras de Cálcio/metabolismo , Trofoblastos/enzimologia , 5'-Nucleotidase/metabolismo , Trifosfato de Adenosina/metabolismo , Transporte Biológico Ativo , Cálcio/metabolismo , Calmodulina/fisiologia , Feminino , Feto/metabolismo , Glucose-6-Fosfatase/metabolismo , Humanos , Transporte de Íons , Cinética , Magnésio/fisiologia , Troca Materno-Fetal , Gravidez , ATPase Trocadora de Sódio-Potássio/metabolismoRESUMO
We investigated the role of intracellular Mg(2+) (Mg(i)(2+)) on the ATP regulation of Na(+)/Ca(2+) exchanger in squid axons and bovine heart. In squid axons and nerve vesicles, the ATP-upregulated exchanger remains activated after removal of cytoplasmic Mg(2+), even in the absence of ATP. Rapid and complete deactivation of the ATP-stimulated exchange occurs upon readmission of Mg(i)(2+). At constant ATP concentration, the effect of intracellular Mg(2+) concentration ([Mg(2+)](i)) on the ATP regulation of exchanger is biphasic: activation at low [Mg(2+)](i), followed by deactivation as [Mg(2+)](i) is increased. No correlation was found between the above results and the levels of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] measured in nerve membrane vesicles. Incorporation of PtdIns(4,5)P(2) into membrane vesicles activates Na(+)/Ca(2+) exchange in mammalian heart but not in squid nerve. Moreover, an exogenous phosphatase prevents MgATP activation in squid nerves but not in mammalian heart. It is concluded that 1) Mg(i)(2+) is an essential cofactor for the deactivation part of ATP regulation of the exchanger and 2) the metabolic pathway of ATP upregulation of the Na(+)/Ca(2+) exchanger is different in mammalian heart and squid nerves.