Magnesium and trace elements (Magnes Trace Elem )

Publisher: American Society for Magnesium Research

Description

  • Impact factor
    0.00
  • 5-year impact
    0.00
  • Cited half-life
    0.00
  • Immediacy index
    0.00
  • Eigenfactor
    0.00
  • Article influence
    0.00
  • Other titles
    Magnesium and trace elements
  • ISSN
    1015-3845
  • OCLC
    21400675
  • Material type
    Periodical
  • Document type
    Journal / Magazine / Newspaper

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: The magnesium content of the adult human is approximately 24 g (1 mol), about half lies in bone and half in soft tissue. Less than 1% of the total body magnesium is present in blood, with approximately 0.3% present in serum. Total magnesium has been determined in several body tissues, but we lack information about free magnesium, which has physiologic significance. Current assessment of magnesium status is difficult as there is no simple, rapid and accurate test(s) to indicate total body magnesium status. I discuss 12 tests in three functional categories that have been used clinically or in research to assess magnesium status. Determining total magnesium in tissues and physiologic tests may provide important information. A test for the routine determination of free magnesium in serum should improve the assessment of magnesium status. A combination of available tests is recommended.
    Magnesium and trace elements 01/1993; 10(2-4):172-81.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effect of acute ethanol perfusion on the intracellular free magnesium level, intracellular pH, and high energy phosphate levels of isolated adult rat hearts (n = 13) were studied using 31P nuclear magnetic resonance (NMR) spectroscopy. Perfusion with 1% ethanol solution resulted in a 43% decrease in the intracellular free magnesium level in Langendorff perfused rat hearts while intracellular pH was not significantly altered. In most hearts ethanol perfusion also resulted in increased intracellular inorganic phosphate and reduced phosphocreatine and ATP levels, corresponding to a significant reduction in phosphorylation potential. The implications of these results in the pathogenesis of alcohol-induced hypertension are discussed in light of our previous studies on spontaneously hypertensive and normotensive rats which demonstrated a correlation between cardiac free magnesium levels and blood pressure.
    Magnesium and trace elements 01/1993; 10(2-4):136-41.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Red blood (RBC) ionized magnesium (Mg2+) was determined by nuclear magnetic resonance (NMR) in order to assess the usefulness of this technique as an index of magnesium depletion. Twenty-four normal subjects underwent a 3-week low-Mg diet. The RBC Mg2+ fell from 209 +/- 9.8 microM before diet to 162 +/- 9.3 microM at the end of the 3 weeks (p < 0.001). In patient populations, 22 hypomagnesemic hospitalized patients had a significantly lower RBC Mg than normal (146 +/- 7.1 microM, p < 0.002), and 37 outpatients with diabetes mellitus had a mean RBC Mg2+ of 172 +/- 7.1 microM which was also significantly lower than normal (p < 0.001). These data suggest that determination of RBC Mg2+ may be used to reflect intracellular Mg status.
    Magnesium and trace elements 01/1993; 10(2-4):117-21.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ion-sensitive microelectrodes (ISEs) have been used to measure intracellular [Mg2+] ([Mg2+]i) in cardiac muscle, although most measurements have tended to overestimate the value due to the poor selectivity of the Mg2+ ionophore in the sarcoplasm and to inaccurate collation of individual ISE measurements. This paper highlights the correct method for analysis of data from multiple ISE experiments. Since [Mg2+]i is constrained at a lower concentration than would be expected by passive distribution of the ion, some of the possible mechanisms underlying Mg2+ extrusion from ferret ventricular myocardium were investigated. During elevation of the extracellular [Mg], mean [Mg2+]i rose from 1.61 to 1.91 mM. The same intervention had no significant effect on membrane potential, intracellular [Na+] or pH measured with ISEs, and there was no change in resting [Ca2+], as assessed from fura-2 fluorescence. The data are not consistent with a simple mechanism for Na(+)-Mg2+ exchange as the primary mode of Mg2+ regulation in cardiac muscle or with an Mg2+ extrusion mechanism involving steady-state ion exchange.
    Magnesium and trace elements 01/1993; 10(2-4):80-9.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The cellular bioenergetic responses of isolated perfused working rat hearts to alterations in hemodynamic function caused by acute exposure to elevated levels of extracellular magnesium ions ([Mg2+]o) were examined using 31P nuclear magnetic resonance (31P NMR) spectroscopy. Results showed that in hearts working against 90 cm H2O afterload, an increase in [Mg2+]o from 1.2 to 4.8 mM reduced the heart rate by 35%, while coronary flow was increased by 38%. Unexpectedly, despite the pronounced bradycardia, the rate-pressure product was reduced only slightly (from 2.36 x 10(4) to 2.08 x 10(4) mm Hg/min) due to a significant increase (36%) in systolic pressure. In addition, cardiac output actually increased by 23%, owing to a > 100% increase in stroke volume, indicating that the performance of the heart was improved and suggesting that the efficiency of the heart was improved as well. In a separate series of experiments, 31P NMR measurements performed on hearts perfused in the Langendorff mode revealed that elevated levels of [Mg2+]o increase phosphocreatine (PCr) levels by 23% (from 9.2 to 11.3 mM), while Pi levels declined by a corresponding amount. Perfusion of hearts in the working mode with elevated [Mg2+]o was also observed to increase PCr levels from 6.3 to 9.0 mM, while ATP levels declined by 17%. Measurement of the chemical shift difference between Pi and PCr and that between the alpha and beta phosphate resonances of ATP were used to determine intracellular pH and the cytosolic levels of free Mg2+ ([Mg2+]i), respectively. These results showed that acute exposure of hearts, perfused in either the working or Langendorff mode, to increased levels of [Mg2+]o increased intracellular pH by 0.12-0.13 units, while free Mg2+ nearly doubled to a level of 1.1-1.2 mM. The latter observation may suggest that acute variations in the level of [Mg2+]o can influence a multitude of cellular processes requiring Mg2+ as an essential cofactor. Using the above data and assuming equilibrium of the creatine kinase reaction, the levels of ADP, cytosolic phosphorylation potential ([ATP]/[ADP][Pi]) and free energy change from ATP hydrolysis (-delta G/delta E) were also calculated. Results obtained illustrate that in the presence of elevated [Mg2+]o, ADP levels declined by 33-48%, the cytosolic phosphorylation potential increased from 41 to 112 mM-1 and -delta G/delta E increased from 56.7 to 59.3 kJ/mol. These changes are not completely accountable by the known bradycardia and vasodilatory effects of elevated [Mg2+]o and strongly argue for a direct action of [Mg2+]o on the myocyte as well.(ABSTRACT TRUNCATED AT 400 WORDS)
    Magnesium and trace elements 01/1993; 10(2-4):99-116.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Magnesium, the second most abundant intracellular cation, is essential for life. The consequences of deficiency are severest in the smallest and youngest members of each species and may include sudden unexpected death. Magnesium deficiency, usually diagnosed by hypomagnesemia, may be congenital, as in premature infants, infants of magnesium-deficient mothers and infants with intrauterine growth retardation. It may be acquired or caused by low magnesium intake, the use of magnesium-wasting drugs, illness provoking gastrointestinal or renal losses of the mineral, or high metabolic demands imposed by catch-up growth or postsurgical healing. Finally, the deficiency may be conditioned, caused by excessive dietary calcium, phosphorus or protein in relation to dietary magnesium, especially during a period of rapid growth or tissue repair. Magnesium therapy is safe when a low dosage is given with monitoring of plasma or serum magnesium levels, with occasional checking of calcium and potassium levels. A parenteral dose of 0.1 ml/kg/day of 50% magnesium sulfate USP (approx. 0.2 mmol/kg/day or 0.4 mEq/kg/day) may be given for 5 dose days. An oral dose of 1.0 ml of 10% magnesium chloride solution providing 0.5 mmol/kg/day magnesium or 1.0 ml/kg/day of 10% magnesium chloride USP (0.5 mmol/kg/day) or magnesium magonate (Magonate) 1.0 ml/kg/day (0.45 mmol/kg/day) may be given for extended periods; higher doses may be required for malabsorption syndromes. Hypermagnesemia, which usually results from magnesium overdosage or inadequate renal function, is a potential threat to neonates born to magnesium-treated eclamptic mothers. Most show marked improvement after 36 h of conservative management that includes calcium salts and intravenous infusions of glucose and saline, but obtunded neonates may require dialysis.
    Magnesium and trace elements 01/1993; 10(2-4):229-50.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The development of fluorescent ion-selective indicators for magnesium has provided valuable tools for measuring second-by-second changes in cytosolic magnesium activity. In the course of establishing appropriate protocols for using one of these indicators, mag-fura-2, to measure magnesium activity in BC3H-1 cells and chick ventricular myocytes, many potential pitfalls and limitations of this technique have been encountered and addressed. These observations are presented for the purpose of providing guidelines regarding the appropriate use of this indicator and on factors influencing the interpretation of resulting data.
    Magnesium and trace elements 01/1993; 10(2-4):142-50.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The reference system, preanalytical variables, specimen requirements and methodology for determination of magnesium in serum by clinical laboratories are discussed. Most clinical laboratories determine the serum magnesium concentration by colorimetric methods. Four different chromophores (calmagite, methylthymol blue, formazan dye and magon) are commonly used for the determination of serum magnesium on automated instruments by clinical laboratories. The College of American Pathologists Proficiency Testing Survey shows that instruments using the chromophore magon have a larger coefficient of variation among laboratories than most instruments using a different chromophore.
    Magnesium and trace elements 01/1993; 10(2-4):60-6.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Magnesium has a profound effect on neural excitability; the most characteristic signs and symptoms of Mg deficiency are produced by neural and neuromuscular hyperexcitability. These create a constellation of clinical findings termed tetany syndrome (TS). TS symptoms include muscle spasms, cramps and hyperarousal, hyperventilation and asthenia. Physical signs (Chvostek's, Trousseau's or von Bonsdorff's) and abnormalities of the electromyogram or electroencephalogram can usually be elicited. Signs and symptoms of TS are frequently encountered in clinical practice, especially among patients with functional or stress-related disorders. The role of Mg deficit in TS is suggested by relatively low levels of serum or erythrocyte Mg and by the clinical response to oral Mg salts, which has been demonstrated in controlled studies. Among the more serious neurologic sequelae of TS are migraine attacks, transient ischemic attacks, sensorineural hearing loss and convulsions. Mg deficiency may predispose to hyperventilation and may sensitize the cerebral vasculature to the effects of hypocarbia. Mg deficiency increases susceptibility to the physiologic damage produced by stress, and Mg administration has a protective effect; studies on noise stress and noise-induced hearing loss are taken as an example. In addition, the adrenergic effects of psychological stress induce a shift of Mg from the intracellular to the extracellular space, increasing urinary excretion and eventually depleting body stores. Drugs used in neurology and psychiatry may affect Mg levels in blood and may diminish signs of tetany, making assessment of Mg status more difficult. Pharmacologic use of Mg can decrease neurologic deficit in experimental head trauma, possibly by blockade of N-methyl-D-aspartate receptors. In conjunction with high doses of pyridoxine, Mg salts benefit 40% of patients with autism, possibly by an effect on dopamine metabolism.
    Magnesium and trace elements 01/1993; 10(2-4):287-301.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The concentration of free Mg2+ in the matrix of isolated heart mitochondria has been monitored using the fluorescent probe furaptra. The techniques used for loading, calibrating and using furaptra fluorescence to monitor matrix free Mg2+ are described. Furaptra is loaded as the membrane-permeable acetoxymethyl ester which is hydrolyzed to the impermeant acid form by nonspecific esterases. Loading is sufficient in a 20-min period at 25 degrees C to give signals approximately 5-fold greater than nonloaded mitochondria. Uncertainties concerning the apparent dissociation constant value for Mg2+ for entrapped furaptra and the ability of ionophores to equilibrate Mg2+ across the mitochondrial membrane are discussed. We conclude that our best estimate for matrix Mg2+ in isolated mitochondria is 0.5 mM and that it can change significantly with changing Mg2+ ligand availability in the matrix.
    Magnesium and trace elements 01/1993; 10(2-4):151-64.
  • Magnesium and trace elements 01/1992; 10:182-192.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Diagnostic categories that are useful for describing patients with acute or organ failure disease are generally less useful labels for primary care and preventive medicine patients whose conditions are better described by signs and symptoms. Symptoms may be clues to ill health but are not often criteria for a major diagnostic labeling. In my practice I have used a computer-based medical record system that permits portrayal and comparison of symptom data to correlate varying degrees of retention of an intramuscular magnesium-loading study (IMMLS) with symptom patterns in 172 patients. The group of patients who show a paradoxical excretion of more Mg than they were given in the IMMLS are a distinctive group with lower blood pressures and significantly fewer digestive and skin symptoms, fewer symptoms of inflammation but more emotional symptoms than those with normal Mg excretion. The group who retained > 49% of the load had higher blood pressures and significantly fewer symptoms of inflammation of the skin and of the reproductive tract.
    Magnesium and trace elements 01/1992; 10(2-4):251-62.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Vanadium has been reported to affect numerous physiological processes; however, a demonstration that vanadium deficiency consistently impairs biological function is lacking. The purpose of this study was to determine if the activity of hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, the rate-limiting enzyme in cholesterol synthesis, is affected by dietary supplementation of vanadate and/or chronic ascorbic acid deficiency. To determine if vanadium and/or ascorbic acid affected mineral metabolism, tissue minerals also were analyzed. Weanling male guinea pigs were assigned randomly to groups of 10 in a 2 x 2 factorial design. The dietary variables were ascorbate, 0.5 or 10 mg/day, and vanadium < 0.01 microgram or 0.5 microgram/g diet as NH4VO3 in a low Cr diet containing < 0.07 microgram Cr/g diet. After 21 weeks on this diet, guinea pigs receiving more ascorbate had lower liver weight/body weight ratios and increased bone copper. Testes weight/body weight ratios, hepatic glycogen and bone copper decreased while hepatic lipids, fecal bile acids, plasma cortisol and bone calcium and magnesium were increased by vanadium supplementation. An interaction between vanadium and ascorbate affected cholesterol excretion in feces, hepatic iron, plasma cholesterol concentration and the activity of HMG CoA reductase. This study provides evidence of increased bone mineral concentrations with vanadium supplementation and of an interaction between vanadium and ascorbate which affected cholesterol metabolism.
    Magnesium and trace elements 01/1991; 10(5-6):327-38.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The development of Cu deficiency after prior exposure for 8 days to normal and high Cu and to normal and high Fe was examined in weanling male Sprague-Dawley rats. After 28 days of Cu depletion, those with high rather than normal initial Cu stores had less elevation in heart and liver weight; higher hemoglobin and hematocrit (by 17%), Cu,Zn-superoxide dismutase activity in liver (44%), cytochrome c oxidase activity in liver (66%) and heart (19%), and Cu concentration in liver (76%) and heart (37%). In contrast, high initial stores of Fe did not alter Cu status during Cu deprivation. Thus, prior exposure to Cu, but not Fe, decreased the severity of Cu deficiency.
    Magnesium and trace elements 01/1991; 10(1):21-9.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A study was performed to determine whether dietary pyridoxine affects the response of rats to arsenic deprivation. A 2 x 2 x 2 factorially arranged experiment utilized groups of 6 male weanling Sprague-Dawley rats. They were fed a 14% amino acid/76% acid-washed corn diet for 10 weeks. The dietary variables were arsenic, 0 or 1 microgram/g; pyridoxine.HCl, 0 or 10 mg/kg, and L-methionine, 0 or 3 g/kg. The basal diet contained 0.24% methionine (calculated) and about 10 ng arsenic/g. Growth was reduced by arsenic, pyridoxine or methionine deprivation. Other parameters including blood indices, erythrocyte aspartate aminotransferase and the concentration of tissue iron and plasma amino acids were affected by dietary arsenic, pyridoxine, methionine or their interaction. The data demonstrate that dietary pyridoxine and arsenic interact and that the methionine status of the animal can affect this interaction.
    Magnesium and trace elements 01/1991; 10(5-6):339-47.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Previous studies on isolated blood vessels indicate that acute withdrawal of extracellular magnesium ions ([Mg2+]o) induces calcium-dependent contractile responses, including coronary blood vessels. The present study, using isolated perfused rat hearts, was designed to assess whether low [Mg2+]o could result in cardiac failure and to gain some insight into the mechanism of action. The results show that both the myocardial oxygen consumption (by 29-38%) and oxygen tension in the coronary effluent decreased (by 18-26%) as the [Mg2+]o was decreased stepwise from 1.2 to 0.6, 0.3 and 0.0 mM. Linear-regression analysis of a plot of coronary flow versus the rate of oxygen consumption shows that there is a tendency for a rightward shift of this relationship in low [Mg2+]o and a leftward shift of the curve in elevated [Mg2+]o (4.8 mM). The experiments also show that with low [Mg2+]o, coronary flow declines 20-37%, and cardiac output and stroke volume fall 24-50% accompanied by 3- to 4-fold elevations in lactate production and eventual, irreversible cardiac failure. An interesting finding, of this study, is that the alpha-adrenoceptor constrictor agonist, phenylephrine (1-5 microM), was found to have effects very similar to low [Mg2+]o. This latter finding is consonant with our hypothesis that progressive lowering of extracellular, ionized magnesium initiates progressive coronary vasoconstriction, decreased tissue oxygenation and myocardial ischemia, which given time, in situ, in the intact host can lead to cardiac failure.
    Magnesium and trace elements 01/1991; 10(5-6):364-73.
  • Magnesium and trace elements 01/1991; 10(1):51-2.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Brief hypoxia or hyperoxia has been shown to affect growth and metabolism of chick embryos during the late stages of development. The objective of this study was to alter the availability of oxygen to chick embryos developing in ovo and to determine the effects on tissue zinc, copper, iron and manganese levels. On day 15 of incubation fertile chicken eggs were divided into three groups: 15% O2 (hypoxic), 60% O2 (hyperoxic) and 21% O2 (normoxic) and incubated under these conditions for 72 h to day 18. Hypoxia reduced embryo, heart, brain and liver wet weights, whereas hyperoxia increased embryo, heart, lung and liver wet weights compared to normoxic controls. Chorioallantoic membrane (CAM) wet weight was increased by hypoxia and reduced by hyperoxia. Livers from hyperoxic embryos contained more zinc, iron and manganese and less copper than livers from hypoxic or normoxic embryos. Tissue concentrations of zinc, copper, iron and manganese were reduced in brains from hyperoxic compared to hypoxic or normoxic embryos. Hyperoxia increased the zinc and copper concentrations in CAM, whereas hypoxia reduced zinc and iron levels. The contents of zinc and copper were increased in hyperoxic compared to normoxic or hypoxic lungs. Hearts from hyperoxic embryos had more zinc, copper and manganese than hypoxic or normoxic hearts. Hypoxic yolk sac contained more zinc and manganese than hyperoxic or normoxic yolk sac. Except for yolk sac, the trace element content of tissues from normoxic embryos increased from day 15 to day 18 of incubation in concert with tissue growth. We conclude that the availability of oxygen to the developing chick embryo affects tissue trace element levels through its effects on tissue growth, as a result of adaptation by specific tissues to different oxygen tensions, or via effects on the regulation of trace element uptake and assimilation by the tissues.
    Magnesium and trace elements 01/1991; 10(5-6):305-20.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hypomagnesemia is the commonest electrolyte abnormality in the ambulatory diabetic patient and is also a frequent finding in patients with diabetic ketoacidosis. Excessive urinary magnesium loss associated with glycosuria is probably the most important factor in the genesis of hypomagnesemia in the diabetic patient. The clinical consequences of magnesium deficiency include impairment of insulin secretion, insulin resistance and increased macrovascular risk. The role of magnesium deficiency in microvascular complications has yet to be clearly defined.
    Magnesium and trace elements 01/1991; 10(2-4):215-9.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The concentration of molybdenum was measured by inductively coupled plasma mass spectrometry (ICPMS) in the urines of two groups of healthy people living in two areas of France, Brest and Paris, about 500 km away. The concentration of Mo in the 24-hour urines of 10 healthy subjects from the Brest region was 25 +/- 10 micrograms/l, 38 +/- 20 micrograms/24 h and 21 +/- 9 micrograms/g creatinine. The concentration of Mo in the morning urines of 23 healthy men of the Paris region was 41 +/- 34 micrograms/l and 21 +/- 15 micrograms/g creatinine. Thus the mean elimination of Mo per gram of creatinine was the same in the two groups (21 +/- 9 and 21 +/- 15). Since the three main isotopes of Mo m/z = 95, 96 and 98, corresponding to an abundance percentage of 16, 17 and 24.5, respectively, were simultaneously analyzed in each sample and led to similar results, the ICPMS method seems reliable.
    Magnesium and trace elements 01/1991; 10(1):47-50.

Related Journals