Total Magnesium Concentrations Research Articles

Effective CO 2-specific sequestration capacity of steel slags and variability in their leaching behaviour in view of industrial mineral carbonation

Industrial mineral carbonation of alkaline wastes, an increasingly promising component of carbon capture and storage, may play an important role as a CO 2 mitigation strategy in the context of climate change. Steelmaking slags are of particular interest owing to their high content of calcium. The cumulated ‘effective’ CO 2-specific sequestration capacity (calculated on the basis of calcium and magnesium extracted to a 0.5 M HNO 3 solution) of three basic oxygen and one electric arc furnace slags generated at steel mills in South Africa was 253 kt CO 2 per annum, which was 25.2% lower than their cumulated ‘theoretical’ capacity (estimated on the basis of total calcium and magnesium content in slags). The mineralogical composition and solubility characteristics of slags conferred very distinct leaching behaviours to the slags, including differences in: (i) the amount of heat generated during their dissolution, (ii) their buffering capacity, (iii) the rate and extent of calcium and magnesium extraction from the slags, and (iv) the mineralogical composition of the non-dissolved residues. These findings suggest that separate leaching processes may need to be developed for slags with largely distinct mineralogical compositions and structural features.

Genetic determinants of extracellular magnesium concentration: Analysis of multiple candidate genes, and evidence for association with the estrogen receptor α ( ESR1) locus

Background Serum magnesium concentration is a quantitative trait with substantial heritability. Although the pool of candidate genes continues to grow, only the histocompatibility locus has been associated with magnesium levels. To explore other possibilities, we targeted 6 candidate genes physiologically relevant to magnesium metabolism. Methods We studied a large cohort ( n = 471) derived from a well-characterized population of healthy Caucasian women 18 to 35 years. Total serum magnesium and calcium were measured by atomic absorption spectrophotometry (aaMg & aaCa). Genomic DNA was amplified and SNPs in candidate genes ( CASR, VDR, ESR1, CLDN16, EGF1, TRPM6) genotyped by routine methods. Results We found a significant association between estrogen receptor α ( ESR1) polymorphisms, PvuII and XbaI, and magnesium ( r = − 0.116, p = 0.012 and r = − 0.126, p = 0.006, respectively). Stratifying by PvuII genotype (P/p alleles), the mean adjusted total magnesium (aaMg) concentration was significantly higher ( p = 0.01) in the pp group (0.823 ± 0.005 mmol/l, n = 130) than in PP homozygotes (0.805 ± 0.006 mmol/l, n = 70), and the mean in Pp heterozygotes was intermediate (0.810 ± 0.005 mmol/l, n = 180). No significant associations were observed with the other candidate genes tested. Conclusions The significant association between magnesium and ESR1 polymorphisms supports previous studies linking physiologic changes in serum magnesium to estrogen status.

Hematology and serum clinical chemistry reference intervals for free‐ranging Scandinavian gray wolves (Canis lupus)

Scandinavian free-ranging wolves (Canis lupus) are endangered, such that laboratory data to assess their health status is increasingly important. Although wolves have been studied for decades, most biological information comes from captive animals. The objective of the present study was to establish reference intervals for 30 clinical chemical and 8 hematologic analytes in Scandinavian free-ranging wolves. All wolves were tracked and chemically immobilized from a helicopter before examination and blood sampling in the winter of 7 consecutive years (1998-2004). Seventy-nine blood samples were collected from 57 gray wolves, including 24 juveniles (24 samples), 17 adult females (25 samples), and 16 adult males (30 samples). Whole blood and serum samples were stored at refrigeration temperature for 1-3 days before hematologic analyses and for 1-5 days before serum biochemical analyses. Reference intervals were calculated as 95% confidence intervals except for juveniles where the minimum and maximum values were used. Significant differences were observed between adult and juvenile wolves for RBC parameters, alkaline phosphatase and amylase activities, and total protein, albumin, gamma-globulins, cholesterol, creatinine, calcium, chloride, magnesium, phosphate, and sodium concentrations. Compared with published reference values for captive wolves, reference intervals for free-ranging wolves reflected exercise activity associated with capture (higher creatine kinase activity, higher glucose concentration), and differences in nutritional status (higher urea concentration).

Magnesium supplementation and bone turnover.

Two-thirds of total body magnesium content is located in the skeleton. Recently, there have been reports that high dietary magnesium intakes are associated with higher bone mineral density. The effect of magnesium supplementation on bone turnover has recently been investigated in young adults. However, the findings from these studies are conflicting. More studies are necessary to better elucidate the role of magnesium in bone health.

The trace element compositions of S-type granites: evidence for disequilibrium melting and accessory phase entrainment in the source

Within individual plutons, the trace element concentrations in S-type granites generally increase with maficity (total iron and magnesium content and expressed as atomic Fe + Mg in this study); the degree of variability in trace element concentration also expands markedly with the same parameter. The strongly peraluminous, high-level S-type granites of the Peninsular Pluton (Cape Granite Suite, South Africa) are the product of biotite incongruent melting of a metasedimentary source near the base of the crust. Leucogranites within the suite represent close to pure melts from the anatectic source and more mafic varieties represent mixtures of melt and peritectic garnet and ilmenite. Trace elements such as Rb, Ba, Sr and Eu, that are concentrated in reactant minerals in the melting process, show considerable scatter within the granites. This is interpreted to reflect compositional variation in the source. In contrast, elements such as LREE, Zr and Hf, which are concentrated within refractory accessory phases (zircon and monazite), show well-defined negative correlations with increasing SiO2 and increase linearly with increasing maficity. This is interpreted to reflect coupled co-entrainment of accessory minerals and peritectic phases to the melt: leucocratic rocks cannot have evolved from the more mafic compositions in the suite by a process of fractional crystallisation because in this case they would have inherited the zircon-saturated character of this hypothetical earlier magma. Trace element behaviour of granites from the Peninsular Pluton has been modelled via both equilibrium and disequilibrium trace element melting. In the disequilibrium case, melts are modelled as leaving the source with variable proportions of entrained peritectic phases and accessory minerals, but before the melt has dissolved any accessory minerals. Thus, the trace element signature of the melt is largely inherited from the reactants in the melting reaction, with no contribution from zircon and monazite dissolution. In the equilibrium case, melt leaves the source with entrained crystals, after reaching zircon and monazite saturation. A significant proportion of the rocks of the Peninsular Pluton have trace element concentrations below those predicted by zircon and monazite saturation. In the case of the most leucocratic rocks all compositions are zircon undersaturated; whilst the majority of the most mafic compositions are zircon oversaturated. However, in both cases, zircon is commonly xenocrystic. Thus, the leucocratic rocks represent close to pure melts, which escaped their sources rapidly enough that some very closely match the trace element disequilibrium melting model applied in this study. Zircon dissolution rates allow the residency time for the melt in the source to be conservatively estimated at less than 500 years.

Correlation between total and ionic magnesium concentration in human serum samples is independent of ethnicity or diabetic state

The relationship between total and ionic serum magnesium in health and chronic disease across different ethnicities has not been well studied. Accordingly, we have examined the interrelationship between total magnesium and ionic magnesium, as well as ionic calcium to ionic magnesium ratio, in 286 patients made up of indigenous and non-indigenous Australians, with or without diabetes. Significant correlations were noted between total and ionic magnesium in all groups (p < 0.001). Amongst people with diabetes, the correlation coefficient (r) was 0.81 whereas in non-diabetics, the r was 0.66. This relationship was independent of whether the sample was from indigenous (r = 0.71) or non-indigenous (r = 0.81) participants. Overall the correlation between total and ionic magnesium across all participants was 0.75. There was no correlation between serum total magnesium and serum ionic calcium (r = 0.07), and similarly none between serum ionic magnesium and serum ionic calcium (r = 0.26). There was, however, a significant negative correlation between the calcium: magnesium ratio and serum total magnesium (r = 0.80; p < 0.001) across all participants, irrespective of whether the sample was made up of indigenous (r = 0.83) or non-indigenous participants (r = 0.77), or of diabetics (r = 0.71) versus non-diabetics (r = 0.83). We conclude that total and ionic magnesium serum concentrations are strongly correlated, and that either gives an accurate assessment of magnesium status in health and chronic diabetes, irrespective of ethnicity.

Idiopathic recurrent calcium urolithiasis (IRCU): variation of fasting urinary protein is a window to pathophysiology or simple consequence of renal stones in situ?

BackgroundIn IRCU it is uncertain whether variation of urinary protein, especially non-albumin protein (NAlb-P), is due to the presence of stones or reflects alteration of oxidative metabolism.AimsTo validate in a tripartite cross-sectional study of 187 ambulatory male patients, undergoing a standardized laboratory programme, whether stones impact on N-Alb-P or the state of oxidative metabolism interferes with IRCU pathophysiology.MethodsIn part 1 the strata low and high of fasting urinary excretion rate per 2 h of N-Alb-P, malonedialdehyde, hypoxanthine, xanthine, pH and other urine components were compared, and association with renal stones in situ evaluated; in part 2 the co-variation of oxidatively modulated environment, fasting urinary pH, calcium (Ca) salt crystallization risk and the number of patients with stones in situ was examined; in part 3, the nucleation of Ca oxalate and Ca phosphate was tested in undiluted postprandial urine of patients and related to the state of oxidative metabolism.ResultsIn part 1, N-Alb-P excretion > 4.3 mg was associated with increase of blood pressure, excretion of total protein, hypoxanthine (a marker of tissue hypoxia), malonedialdehyde (a marker of lipid peroxidation), sodium, magnesium, citrate, uric acid, volume, pH, and increase of renal fractional excretion of both NAlb-P and uric acid; when stones were present, urinary pH was elevated but other parameters were unaffected. Significant predictors of N-Alb-P excretion were malonedialdehyde, fractional N-Alb-P and hypoxanthine. In part 2, urine pH > 6.14 was associated with unchanged blood pressure and plasma vasopressin, increase of blood pH, urinary volume, malonedialde hyde, fractional excretion of N-Alb-P, uric acid, Ca phosphate, but not Ca oxalate, supersaturation; this spectrum was accompanied by decrease of concentration of urinary total and free magnesium, total and complexed citrate, plasma uric acid (in humans the major circulating antioxidant) and insulin; the number of stone-bearing patients was increased. Significant predictors of urine pH were body mass index, plasma insulin and uric acid (negative), and urinary xanthine (positive). In part 3 low plasma uric acid, not high urinary malonedialdehyde or high ratio malonedialdehyde/uric acid was significantly associated with diminished Ca but not oxalate tolerance, with the first nucleating crystal type being mostly Ca phosphate (hydroxyapatite), in the rest Ca oxalate dihydrate; uricemia correlated marginally positively (p = 0.055) with Ca tolerance of urine, stronger with blood pressure and insulin, and negatively with urinary xanthine, fractional N-Alb-P, volume, sodium.ConclusionsIn IRCU 1) not renal stones in situ, but disturbed oxidative metabolism apparently modulates nephron functionality, ending up in higher renal NAlb-P release, urinary volume, sodium and pH of fasting urine; 2) etiologically unknown decline of uricemia may represent antioxidant deficiency and cause a risk of hydroxyapatite crystallization and stone formation in a weakly acidic or alkaline inhibitor-deficient and NAlb-P-rich milieu; 3) several observations, linking oxidative and systemic metabolism, are compatible with Ca stone initiation beyond tubules.

Effect of various anesthetic induction agents on blood magnesium and calcium concentration.

Decrease in blood magnesium and calcium concentration is associated with an increase in the incidence of arrhythmia, especially during the induction period. Therefore, it is important to evaluate the effects of propofol, pentothal sodium, and sevoflurane on calcium and magnesium concentration. Thirty-six premedicated, ASA grade I patients were selected and randomly allocated into 3 groups. Six percent sevoflurane inhalation (sevo group), propofol 1.5 mg/kg (propofol group), and 5 mg/kg of pentothal sodium (pento group) were administered for anesthetic induction and anesthetic maintenance was done with end-tidal sevoflurane concentration at 3.5%. Blood sampling was performed during the pre-induction period (pre-induction), just before tracheal intubation (pre-intubation), and 2 min after intubation (post-intubation). pH corrected ionized magnesium and calcium were calculated and analyzed simultaneously. Both total calcium and magnesium concentrations decreased significantly in all groups during the pre-intubation and post-intubation periods compared with the pre-induction period. Ionized calcium only decreased significantly during pre-intubation and post-intubation in the pento group, and did not change throughout the study period in the sevo and propofol groups. Ionized magnesium did not change throughout the study period in any of the groups. pH corrected ionized calcium decreased significantly only at post-intubation in the pento group. All anesthetic induction agents administered in this study can be used safely in terms of magnesium-associated arrhythmia. However, ionized calcium concentration decreased in the pento group, but all values were within normal limits. This finding indicated that it is safe to use propofol, pentothal sodium, and sevoflurane for anesthetic induction.

Magnesium homeostasis and alcohol consumption.

Clinical and experimental evidence indicates alcohol consumption as one of the major causes of magnesium loss from several tissues. As a result of this loss, serum magnesium tends to decrease while urinary magnesium excretion increases 2-3 fold. Experimental data confirm that chronic consumption of 6% ethanol in the Lieber De-Carli diet for 3 weeks results in a marked decrease in total tissue magnesium content in rats. This decrease affects brain, liver and all skeletal muscle, including heart, to a varying extent. While a full picture of the implications of magnesium loss in these tissues is still lacking, it is becoming progressively clear that magnesium loss affects energy production, protein synthesis, cell cycle, and specific functions in the various organs affected. In addition, as magnesium regulated cytokine production and secretion, especially in macrophages and leukocytes, a major role of magnesium deficiency in alcohol-induced inflammatory processes can be envisioned. Considering all these various aspects together, it becomes apparent that magnesium loss may represent a predisposing factor to the onset of alcohol-induced pathologies including brain stroke, sarcopenia, cardiomyopathy, steatohepatitis and cirrhosis. The present review will attempt to clarify some of the mechanisms by which ethanol impairs magnesium transport and homeostasis in brain, brain vasculature, skeletal muscle, heart and liver cells, as a first step towards more mechanistic studies aimed at relating magnesium loss with the incurrence of short- and long-term ethanol-induced complications in these organs.

Growth and photosynthetic responses to zinc stress of an invasive cordgrass, Spartina densiflora

Spartina densiflora Brongn. is found in coastal marshes of southwest Spain, growing over sediments containing 100-4800 ppm Zn. A glasshouse experiment was designed to investigate the effect of Zn from 0 to 100 mmol.l(-1) on the growth and photosynthetic apparatus of S. densiflora, by measuring relative growth rate, leaf elongation rate, number of tillers, height of tillers, chlorophyll fluorescence parameters, gas exchange and photosynthetic pigment concentrations. We also determined total ash, Zn, calcium, magnesium and phosphorus concentrations, and the C/N ratio. At 100 mmol.l(-1) Zn, S. densiflora showed a 48% biomass reduction after 1 month of treatment. Long-term effects of Zn on growth of S. densiflora consisted mainly of variations in net photosynthesis. Modification of the Zn/Mg ratio was linked to a strong decrease in RuBP carboxylase (Zn was favoured in local competition with Mg, so that the affinity of RuBisCO for CO(2) decreased), oxygenase activity of RuBisCO acting as a substitute for the photosynthetic function. Also, Zn had a marked overall effect on the photochemical (PSII) apparatus and the synthesis of photosynthetic pigments. However, the results indicate that S. densiflora is capable of tolerating very high and continued exposure to Zn, as this species lowers the translocation of Zn from the nutrient solution to roots and controls Zn ion transport into leaves. Therefore, S. densiflora could be useful in the phytostabilization of soils.

Growth and photosynthetic responses to copper stress of an invasive cordgrass, Spartina densiflora

Spartina densiflora Brongn. is found in coastal marshes of south-west Spain, growing in sediments with between 300 and 3000 mg Cu kg −1 total soil DW (450–4500 mg Cu kg −1 supposing that the soil porosity is 0.5). An experiment was designed to investigate the effect of copper from 0 to 5000 mg kg −1 (64 mmol l −1) on the photosynthetic apparatus and the growth of S. densiflora. We also determined total ash, copper, calcium, magnesium and phosphorous concentrations, as well as C/N ratio. S. densiflora survived to concentrations as high as 320 mg Cu kg −1 DW in leaves, although excess of Cu diminished water use efficiency and Ca-, Mg- and P-uptake. Also, quantum efficiency of PSII, net photosynthetic rate, stomatal conductance and pigment concentrations declined with increasing external Cu. Finally, the decline in the photosynthetic function resulted in a biomass reduction of between 50 and 80% (for 600 and 5000 mg Cu kg −1, respectively).

Calcium, vitamin D supplements with or without alendronate and supragingival calculus formation in osteoporotic women: a preliminary study

Objectives: Long-term calcium intake is related to the formation of urinary stones. Structure and composition of kidney and gallstones are similar to dental calculus. Saliva is the source of calcium for supragingival dental calculus formation. The aim of this preliminary study was to evaluate the possible effects of long-term calcium and vitamin D supplementation with or without alendronate administration on salivary electrolyte concentrations and supragingival calculus formation in osteoporotic women. Methods: Thirty-one female patients with osteoporosis for at least 3 years participated in this study. Eighteen women were taking calcium plus vitamin D plus alendronate, while 13 women were taking only calcium plus vitamin D supplements. Eleven systemically healthy women volunteered for the control group. Whole saliva samples were collected from all women before initiation of any periodontal intervention. Plaque index, probing depth, clinical attachment level, bleeding on probing, and calculus index were recorded at six sites/tooth. Salivary concentrations of ionic calcium, potassium, magnesium and sodium were determined by atomic absorption spectrophotometer. Results were evaluated statistically by non-parametric tests. Results: No significant differences were found in clinical parameters or results of saliva analysis between the study groups (p > 0.05). Conclusion: Within the limits of this preliminary study, it is suggested that long-term calcium and vitamin D supplementation with or without alendronate does not appear to have a significant effect on supragingival calculus formation or saliva total calcium, potassium, magnesium and sodium concentrations. Larger-scale studies investigating the possible effects of various treatment modalities of osteoporosis on supragingival calculus formation are required to better clarify this issue.

Untersuchungen zur Prophylaxe der Gebärparese mit Kalzium und Natriumphosphat per os

The goal of this study was to investigate the efficacy of calcium chloride, sodium phosphate or a combination of these two substances administered orally immediately postpartum for the prevention of parturient paresis in cows. Thirty-two cows that had had parturient paresis at the previous calving, and in which serum biochemistry had shown hypocalcaemia and hypophosphataemia, were used in the study. The cows were transferred to the Department of Farm Animals, University of Zurich, five days before their expected due dates. On a randomized trial, the cows were given calcium chloride, sodium phosphate, both substances or no treatment (controls) via a stomach tube immediately postpartum and 12 hours later. The cows were monitored for 96 hours during which time blood was collected on a regular basis for the determination of total calcium, ionized calcium, inorganic phosphorus and magnesium concentrations. Of the 32 cows treated, 19 (59%) had parturient paresis and 13 (41%) did not. The incidence of parturient paresis did not differ significantly among the groups although there was a tendency for a lower incidence in cows treated with both calcium chloride and sodium phosphate. The various treatments had no apparent effect on serum calcium concentration. The concentration of inorganic phosphorus increased significantly in cows treated with sodium phosphate compared with the controls. The results of this study showed that cows treated with both calcium chloride and sodium phosphate orally tended to have a lower incidence of parturient paresis. Further investigation into multiple administrations of oral calcium chloride and sodium phosphate, started before parturition, for the prevention of parturient paresis is required.

Aplicação foliar de cálcio em pessegueiro na Serra Gaúcha: avaliação do teor de nutrientes na folha, no fruto e produção

Na região Sul do Brasil, as aplicações foliares de cálcio têm sido usadas durante o ciclo produtivo do pessegueiro. Entretanto se carece de conhecimentos sobre o teor de cálcio e de outros nutrientes na folha, usada para estimar o estado nutricional da planta, no fruto, utilizado como referência para definir a ocorrência de distúrbio fisiológico e na produção. O trabalho objetivou avaliar o efeito de pulverizações foliares de diferentes fontes de cálcio no seu teor e de outros nutrientes nas folhas, nos frutos e na produção. O trabalho compreendeu dois experimentos e foi conduzido na safra agrícola de 2003/2004, em um pomar comercial de pessegueiro da cultivar Chimarrita, em Pinto Bandeira-RS, sobre um Cambissolo Húmico. O experimento 1 consistiu de uma, duas e três pulverizações foliares de cloreto de cálcio nas concentrações de 0 (água); 0,5; 1,0 e 2,0%. O experimento 2 compreendeu uma, duas e três pulverizações foliares de nitrato de cálcio nas concentrações de 0 (água); 0,5; 1,0 e 2,0%. O delineamento experimental usado nos dois experimentos foi de blocos ao acaso, com três repetições e três plantas por parcela, que foram distribuídas ao longo da linha de plantio. Nas plantas dos dois experimentos, foram coletadas folhas completas (limbo+pecíolo) do terço médio dos ramos do ano, nos diferentes lados da planta, secas, moídas e preparadas para a análise dos teores de cálcio, nitrogênio, potássio e magnésio. Na maturação completa, os frutos foram colhidos e determinados a massa, a produção e os teores de cálcio, nitrogênio, potássio e magnésio. Os resultados mostraram que as aplicações foliares de cloreto de cálcio e nitrato de cálcio durante o ciclo produtivo do pessegueiro aumentaram o teor de cálcio na folha. Porém, não afetaram o teor de nitrogênio, potássio e magnésio na folha, o teor de cálcio, nitrogênio, potássio e magnésio no fruto e na produção.

SLC41A1 Is a Novel Mammalian Mg2+ Carrier

The molecular biology of mammalian magnesium transporters and their interrelations in cellular magnesium homeostasis are largely unknown. Recently, the mouse SLC41A1 protein was suggested to be a candidate magnesium transporter with channel-like properties when overexpressed in Xenopus laevis oocytes. Here, we demonstrate that human SLC41A1 overexpressed in HEK293 cells forms protein complexes and locates to the plasma membrane without, however, giving rise to any detectable magnesium currents during whole cell patch clamp experiments. Nevertheless, in a strain of Salmonella enterica exhibiting disruption of all three distinct magnesium transport systems (CorA, MgtA, and MgtB), overexpression of human SLC41A1 functionally substitutes these transporters and restores the growth of the mutant bacteria at magnesium concentrations otherwise non-permissive for growth. Thus, we have identified human SLC41A1 as being a bona fide magnesium transporter. Most importantly, overexpressed SLC41A1 provide HEK293 cells with an increased magnesium efflux capacity. With outwardly directed Mg(2+) gradients, a SLC41A1-dependent reduction of the free intracellular magnesium concentration accompanied by a significant net decrease of the total cellular magnesium concentration could be observed in such cells. SLC41A1 activity is temperature-sensitive but not sensitive to the only known magnesium channel blocker, cobalt(III) hexaammine. Taken together, these data functionally identify SLC41A1 as a mammalian carrier mediating magnesium efflux.

Characteristics and mechanisms of phosphate adsorption onto basic oxygen furnace slag

The adsorption characteristics of phosphate adsorption on the basic oxygen furnace (BOF) slag were identified as a function of pH and ion strengths in solution. In addition, adsorption mechanisms were investigated by conducting batch tests on both the hydrolysis and phosphate adsorption process of the BOF slag, and making a comparative analysis to gain newer insights into understanding the adsorption process. Results show that the adsorption capacity from 4.97 to 3.71 mg P/g slag when the solution pH was increased from 2.0 to 13.0 and phosphate initial concentration was 50 mg/L, indicating that adsorption capacity is largely dependent upon the pH of the system. The results of the competitive adsorption between phosphate and typical anions found in wastewater, such as NO 3 −, SO 4 2− and Cl −, onto BOF slag reveal that BOF slag can selectively adsorb phosphate ions. The insignificant effect of NO 3 −, SO 4 2− and Cl − on phosphate adsorption capacity indicates that phosphate adsorption is through a kind of inner-sphere complex reaction. During the adsorption process, the decrease of phosphate concentration in solution accompanied with an increase in pH values and concentrations of NO 3 −, SO 4 2− and Cl − suggests that phosphate replaced the functional groups from the surface of BOF slag which infers that ligand exchange is the dominating mechanism for phosphate removal. At the same time, the simultaneous decreases in PO 4 3− and total calcium, magnesium and aluminum concentration in solution indicate that chemical reaction and precipitation are other mechanisms of phosphate removal.

Sistema radicular do capim-tanzânia adubado com potássio e magnésio

Um experimento em casa de vegetação foi conduzido no período da primavera de 2004 visando à obtenção de informações relativas aos atributos do sistema radicular de Panicum maximum Jacq. cv. Tanzânia adubado com combinações de potássio e magnésio em solução nutritiva. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições, em esquema fatorial 5² incompleto, com 13 combinações de doses de potássio e magnésio, em mmol/L: 0,4K/0,05Mg; 0,4K/1,35Mg; 0,4K/2,65Mg; 3,2K/0,70Mg; 3,2K/2,00Mg; 6,0K/0,05Mg; 6,0K/1,35Mg; 6,0K/2,65Mg; 8,8K/0,70Mg; 8,8K/2,00Mg; 11,6K/0,05Mg; 11,6K/1,35Mg e 11,6K/2,65Mg. Após o segundo corte das plantas, realizou-se a coleta das raízes, utilizando-se água corrente e água desionizada com auxílio de peneiras de 0,25 e 1,00 mm. As combinações de doses de potássio e de magnésio foram determinantes para a produção de matéria seca de raízes, o comprimento radicular, a concentração de magnésio nas raízes e as concentrações conjuntas de potássio, magnésio e cálcio. De forma isolada, as doses de potássio alteraram a superfície radicular, o comprimento e a superfície radicular específicos e a concentração de potássio nas raízes. As doses de magnésio, isoladamente, promoveram aumento na superfície radicular e decréscimo na concentração de cálcio nas raízes. As maiores respostas do sistema radicular do capim-tanzânia foram obtidas com o fornecimento de potássio de 6,0 a 8,8 mmol/L e de magnésio de 1,4 a 2,0 mmol/L na solução nutritiva. A participação do potássio foi de 35 a 53% e a do magnésio em torno de 20% na concentração total de potássio, magnésio e cálcio nas raízes.

Thiopental and halothane dose-sparing effects of magnesium sulphate in dogs

ObjectiveTo evaluate the effect of pre- and intraoperatively administered magnesium sulphate (MgSO4) on the induction dose of thiopental and of halothane for maintenance of anaesthesia in dogs undergoing ovariohysterectomy (OHE). Study designProspective, double-blind, randomized, placebo-controlled study. AnimalsForty-six healthy, ASA physical status 1 dogs, scheduled for elective OHE. MethodsThe dogs were randomly assigned to receive a bolus of 50 mg kg−1 MgSO4 intravenously (IV), just before induction of anaesthesia, followed by a constant rate infusion (CRI) of 12 mg kg−1 hour−1 MgSO4 intraoperatively (group Mg, n = 27) or a placebo bolus and CRI of 0.9% sodium chloride (NaCl) (group C, n = 19), approximately 30 minutes after premedication with acepromazine (0.05 mg kg−1, intramuscularly, IM) and carprofen (4 mg kg−1, subcutaneously, SC). Anaesthesia was induced with thiopental administered to effect and maintained with halothane in oxygen. End-tidal halothane (EThal) was adjusted to achieve adequate depth of anaesthesia. Blood samples were obtained pre- and postoperatively for measurement of total serum magnesium concentration. ResultsThe mean dose of thiopental was statistically lower (p < 0.0005) and the mean standardized EThal concentration and end-tidal carbon dioxide partial pressure (Pe′CO2) areas under the curve were statistically smaller (p < 0.0005 and 0.014 respectively) in group Mg. Postoperatively the mean total serum magnesium concentration was statistically higher than the preoperative value (p < 0.0005) in group Mg, but not in group C. Nausea, associated with the MgSO4 bolus injection, was observed in six dogs in group Mg, two of which vomited prior to induction of anaesthesia. Conclusions and clinical relevanceMagnesium sulphate administration reduced the induction dose of thiopental and EThal concentration for maintenance of anaesthesia in dogs undergoing OHE. Observed side effects were nausea and vomiting.

Ionized and total magnesium concentration in patients with severe pre-eclampsia-eclampsia undergoing magnesium sulfate therapy

Ionized and total magnesium concentration in patients with severe pre-eclampsia-eclampsia undergoing magnesium sulfate therapy

The Cardiovascular Depression Caused by Bee Venom in Sprague–Dawley Rats Associated with a Decrease of Developed Pressure in the Left Ventricular and the Ratio of Ionized Calcium/Ionized Magnesium

Bee venom (BV) has been used in Oriental medicine to treat inflammatory diseases, such as tendonitis, bursitis, and rheumatoid arthritis, despite the sensitivity of the victims and toxicity of the venom. This study examined the mechanisms for the effects of BV on the cardiovascular system in rats. The arterial pressure and heart rate (HR) were measured in anesthetized rats. In addition, the left ventricular development pressure (LVDP) and total magnesium efflux ([Mg]e) in isolated perfused hearts, the vascular tonic responses in the isolated aorta, and the blood ionic and biochemical changes were determined simultaneously. In the anesthetized rats, the mean arterial pressure, systolic pressure, and pulse pressure were reduced by BV in a dose-dependent manner, even though the HR was increased. BV had no effects on the relaxation of phenylephrine- or KCl-induced contraction of the aortic rings. In the isolated hearts, BV generated a reversible decrease in the LVDP and velocity with changes in pressure, which were accompanied by increases in the HR and [Mg]e. BV increased the plasma ionized and total magnesium concentrations, and decreased the total magnesium level in the red blood cells. The ratio of ionized calcium/ionized magnesium was also decreased by the BV treatment. BV caused a detectable increase in blood creatine kinase, glutamic oxaloacetic transaminase, and lactic dehydrogenase, as well as a decrease in the blood total protein albumin and globulin levels. These results suggest that BV induces cardiovascular depression by decreasing the cardiac pressure and increasing the ionized magnesium concentration in the blood.