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PubMed2000

Effect of magnesium supplementation on the fractional intestinal absorption of 45CaCl2 in women with a low erythrocyte magnesium concentration.

The cosupplementation of magnesium with calcium has been suggested to be beneficial in the prevention of osteoporosis. We investigated the effect of magnesium supplementation on parameters of bone resorption and fractional 45Ca absorption. Twenty apparently healthy women with a mean age of 39.2 +/- 9.2 years and an erythrocyte magnesium concentration less than 1.97 mmol/L were recruited into a controlled magnesium supplementation trial. During weeks 1 to 4, they received a daily control preparation, potassium/sodium citrate malate (PSCM). During weeks 5 to 8, the subjects received magnesium citrate malate (MCM) equivalent to 250 mg magnesium per day. During the fourth and eighth weeks, blood was collected for measurement of the serum intact parathyroid hormone (PTH) concentration and serum and erythrocyte magnesium concentration. Urine was collected for measurement of calcium, magnesium, creatinine, and deoxypyridinoline excretion. On the final day of each treatment period, 5 microCi45CaCl2 was administered orally, and the isotope was traced in the blood and urine over 7 hours. Urinary calcium, 45Ca, and deoxypyridinoline excretion, as well as serum intact PTH levels, showed no statistically significant changes as a result of magnesium supplementation. However, urinary magnesium excretion increased by 31.1% (P < .005) while fractional 45Ca absorption decreased by 23.5% (P < .001) as a result of magnesium supplementation. It is concluded that magnesium supplementation does not result in changes in bone resorption, while the fractional intestinal absorption of 45Ca appears to decrease.

Adult↗
PubMed1998

Magnesium in drinking water and body magnesium status measured using an oral loading test.

Epidemiological studies have shown an inverse relationship between magnesium in drinking water and death from ischaemic heart disease. The question is whether magnesium in drinking water can be critical for the body magnesium status. The aim of this study was to investigate, using an oral loading test, whether a change in body magnesium status could be found among people who change from drinking water with a low magnesium concentration to water with higher concentrations. The subjects participating in the study were 9 men and 3 women 65-70 years old, living in the city of Göteborg, Sweden, where the magnesium concentration in the tap water is low (1.6 mg/l). Drinking water was prepared with 200 mg MgCl2 x 6H2O added per litre to a level of 25 mg/l, and was distributed to the subjects twice a week for 6 weeks. Excretion of magnesium, potassium and creatinine, basal and after oral magnesium loading (tablets containing 575 mg), was measured in 24 h urine before and after the supplementation period. Calculations were made for the total excretion (mmol/24 h), and in relation to creatinine. The subjects' intake of magnesium via food and water was estimated using a questionnaire. There was a difference between the post load excretion of magnesium, expressed as the magnesium/creatinine ratio, before and after the supplementation period. The mean percentage change was a 14.6% (p=0.047) increase. No changes were found for potassium. In summary, the results indicate that magnesium in drinking water can affect body magnesium status.

Aged↗
PubMed1986

Acute effect of salmon calcitonin on renal magnesium transport in the magnesium-loaded rat.

The present studies were undertaken to examine whether salmon calcitonin, by increasing magnesium reabsorption in the thick ascending limb, and presumably the tubulointerstitial magnesium concentration gradient, would lead to an increase in fractional magnesium delivery to the end-descending limb (magnesium secretion) in magnesium-loaded rats. Thyroparathyroidectomized, postprandial Munich--Wistar rats were prepared for micropuncture of papillary end-descending limbs and of superficial end-accessible proximal tubules. Group 1 served as clonidine-water diuresis time controls; group 2 was treated as group 1 but also received synthetic salmon calcitonin (10 mU/min); and group 3 was treated as group 2 but also received calcium chloride intravenously. Calcitonin, alone or with calcium, produced a significant fall in fractional magnesium excretion. A significant relationship was also observed between fractional magnesium excretion and urine flow rate (r = 0.56, p less than 0.01). Calcitonin did not modify fractional magnesium delivery to the end-descending limb. A highly significant relationship was observed between tubule fluid-to-ultrafiltrate magnesium ratio and tubule fluid-to-plasma inulin ratio (r = 0.88, p less than 0.001). Within each group, fractional magnesium delivery to the end-descending limb was similar to the corresponding value in the superficial end-accessible proximal tubule. Our results suggest that despite intense magnesium reabsorption, presumably in the thick ascending limb, magnesium secretion does not occur in the juxtamedullary pars recta and (or) thin descending limb.

Absorption↗
PubMed1987

Absorption of magnesium from orally administered magnesium sulfate in man.

The use of magnesium sulfate (Epsom salt) as a cathartic in patients with impaired renal function can lead to severe toxicity due to hypermagnesemia. Although toxicity is uncommon in healthy subjects, little is known concerning the extent of absorption of magnesium after a cathartic dose of magnesium sulfate. The bioavailability of magnesium following a large oral dose of magnesium sulfate in normal volunteers was examined in the present investigation. Baseline 24-hour urinary excretion rates of magnesium and creatinine were determined over 3 consecutive days in 6 healthy men. The oral administration of 13.9 g (56.5 mmoles) magnesium sulfate U.S.P., in 4 equal hourly increments, resulted in the urinary excretion (corrected for baseline excretion rate) of 4.0 +/- 2.9% (mean +/- SD) of the dose of magnesium during the first 24 hours and 6.9 +/- 7.0% of the dose during a 72-hour interval. Magnesium sulfate administration had no effect on the 24-hour urinary excretion rate of creatinine. The baseline excretion rate of magnesium was significantly correlated with that of creatinine (r = 0.875) and inorganic sulfate (r = 0.921). All of the subjects experienced mild or moderate diarrhea. Therefore, magnesium is absorbed to a limited and variable extent in healthy adults following a cathartic dose of magnesium sulfate.

Administration, Oral↗
PubMed2002

Relationship between the serum parathyroid hormone and magnesium levels in continuous ambulatory peritoneal dialysis (CAPD) patients using low-magnesium peritoneal dialysate.

BACKGROUND: Patients on continuous ambulatory peritoneal dialysis (CAPD) have increased risk of low-turnover bone disease and relative hypoparathyroidism. Recently, it has been believed that magnesium plays an important role in regulating secretion of parathyroid hormone (PTH). The aim of this study was to evaluate the relationship between serum PTH and serum magnesium as a factor increasing the frequency of relative hypoparathyroidism. METHODS: We analyzed the data of 56 patients who had been on CAPD for more than 6 months without any significant problems. No patient had been previously treated with vitamin D or aluminum hydroxide. The patients had used peritoneal dialysate with the magnesium concentration of 0.5 mEq/L. Biochemical parameters, such as BUN, creatinine, alkaline phosphatase bony isoenzyme, total protein, albumin, total calcium, ionized calcium and intact parathyroid hormone level were measured. RESULTS: The mean serum magnesium level was 1.99 +/- 0.36 mEq/L. Among total 56 patients, 15 patients (26.8%) showed hypermagnesemia (serum magnesium > 2.2 mEq/L) and 5 patients (8.9%) showed hypomagnesemia (serum magnesium < 1.6 mEq/L). Among all 56 patients, serum iPTH (intact PTH) level was not correlated with serum magnesium level. However, it was inversely correlated with serum total calcium and ionized calcium levels, respectively (r = -0.365, p = 0.006; r = -0.515 p < 0.001). Among 49 patients whose serum iPTH level was less than 300 pg/mL, serum iPTH level was inversely correlated with serum magnesium level (r = -0.295, p = 0.039) and inversely correlated with serum total calcium and ionized calcium levels, respectively (r = -0.546, p < 0.001; r = -0.572 p < 0.001). Among 49 patients whose serum iPTH level was less than 300 pg/mL, lower iPTH group (serum iPTH < 120 pg/mL) showed higher serum magnesium level (p = 0.037), higher serum total calcium level (p < 0.001) and lower bone isoenzyme of alkaline phosphatase level (p < 0.001) than those of higher iPTH group (120 pg/mL < or = serum iPTH < 300 pg/mL). CONCLUSION: Among the CAPD patients whose serum iPTH level was less than 300 pg/mL, there was a significant inverse correlation between serum iPTH level and serum magnesium level. This study indicates that not only serum calcium level but also serum magnesium level are important in the regulation of serum iPTH levels of CAPD patients who have been dialyzed by low-magnesium peritoneal dialysate.

Adult↗
PubMed1999

Alterations in ionized and total blood magnesium after experimental traumatic brain injury: relationship to neurobehavioral outcome and neuroprotective efficacy of magnesium chloride.

Experimental evidence suggests that magnesium plays a role in the pathophysiological sequelae of brain injury. The present study examined the variation of blood ionized and total magnesium, as well as potassium, sodium, and ionized calcium, after experimental fluid percussion brain injury in rats. Blood ionized magnesium concentration significantly declined from 0.45 +/- 0.02 to 0.32 +/- 0.02 mM by 30 min postinjury and stayed depressed for the 24-h study period in vehicle-treated rats. Blood total magnesium concentration was 0.59 +/- 0.01 mM and remained stable over time in brain-injured vehicle-treated animals. When magnesium chloride (125 micromol/rat) was administered 1 h postinjury, ionized magnesium levels were restored by 2 h postinjury and remained at normal values up to 24 h following brain trauma. Magnesium treatment also significantly reduced posttraumatic neuromotor impairments 1 and 2 weeks after the insult, but failed to attenuate spatial learning deficits. A significant positive and linear correlation could be established between ionized magnesium levels measured 24 h postinjury and neuromotor outcome at 1 and 2 weeks. We conclude that acute ionized magnesium measurement may be a predictor of long-term neurobehavioral outcome following head injury and that delayed administration of magnesium chloride can restore blood magnesium concentration and attenuate neurological motor deficits in brain-injured rats.

Animals↗
PubMed2000

[Subcutaneous magnesium pump in a patient with combined magnesium transport defect].

HISTORY AND ADMISSION FINDINGS: A 28-year-old man, known to have abnormal intestinal magnesium absorption, presented with recurrent cerebral seizures. Despite daily intravenous sulphate infusions, magnesium concentration remained inadequate. Physical examination was unremarkable. INVESTIGATIONS: Serum magnesium concentration was markedly reduced to 0.48 mmol/l. The parenteral magnesium tolerance test indicated reduced enteric magnesium absorption of < 20%. Absolute magnesium concentration in 24-hour urine was normal at 6.3 mmol/24 h, but high in proportion to the hypomagnesaemia. All other laboratory data were within normal limits. TREATMENT AND COURSE: In addition to the known intestinal malabsorption the patient also had isolated renal loss of magnesium. It was only by continuous magnesium infusion with a recently developed portable subcutaneous pump system that normal serum magnesium concentrations were attained and all symptoms disappeared. CONCLUSION: This patient has combined magnesium transport defects, which could not be effectively treated by conventional methods, but required continuous magnesium infusion with an indwelling subcutaneous infusion pump. This case serves as an example of the way in which subcutaneous infusion can provide physiological substitution of electrolytes.

Adult↗
PubMed2005

Is serum magnesium estimate necessary in patients with eclampsia on magnesium sulphate?

The therapeutic index of magnesium is said to be low, hence, there are fears of toxicity when used as anticonvulsant in eclamptic patients. The objective of this study was to determine the serum levels of magnesium in eclamptic patients treated with magnesium sulphate and relate the levels with clinical indicators. It was a prospective study involving consecutive eclamptic patients that were managed between January and December 2002, with magnesium sulphate as the sole anticonvulsant agent, using a modified Pritchard regimen. Blood samples were taken before the administration of the loading and maintenance doses of magnesium sulphate and serum levels of magnesium were estimated using the Jenway 605 colorimeter. There were 19 patients and 72 blood samples. The mean baseline serum magnesium was 0.72 +/- 0.10 mmol/L while serum magnesium levels when the patients were on treatment ranged from 1.95 to 2.82 mmol/L. No serum magnesium level was greater than 3.0 mmol/L and none of the patients had clinical evidence of magnesium toxicity. We conclude that serum magnesium levels in these patients were within the therapeutic range, therefore, routine estimation of this cation is not necessary. Even where the laboratory facility is available, it is suggested that serum estimation be limited to cases where clinical monitors suggest toxicity.

Adolescent↗
PubMed1994

Erythrocyte and mononuclear blood cell magnesium concentrations are normal in hypomagnesemic patients with chronic renal magnesium wasting.

OBJECTIVE: The purpose of this study was to determine the plasma, erythrocyte, and mononuclear blood cell (MBC) magnesium concentrations in patients with chronic, severe hypomagnesemia due to a chronic magnesium-wasting tubulopathy. METHODOLOGY: Six patients with Bartter's syndrome and five patients with magnesium-wasting tubulopathy were compared with normal subjects. We determined magnesium in plasma, erythrocytes, and MBCs. RESULTS: Patients with chronic magnesium-wasting tubulopathy had a significantly lower plasma magnesium concentration than controls, but erythrocyte magnesium concentration and MBC magnesium concentration and content did not differ significantly between patients and controls. CONCLUSION: Two disorders with chronic magnesium-wasting tubulopathies are associated with a low plasma magnesium concentration but normal erythrocyte and MBC magnesium.

Bartter Syndrome↗
PubMed1991

Blood pressure response during long-term treatment with magnesium is dependent on magnesium status. A double-blind, placebo-controlled study in essential hypertension and in subjects with high-normal blood pressure.

Both experimental and epidemiological studies support the idea of magnesium supplementation in essential hypertension. We added 15 mmol Mg to a free diet in 71 subjects with mild essential hypertension or a high-normal blood pressure in a double-blind, placebo-controlled study over 6 months. The treatment, which raised urinary magnesium excretion 30%, induced no general effects on the blood pressure. However, when the changes in blood pressure in the actively treated group were related to the pretreatment magnesium status, a correlation was found between pretreatment urinary magnesium excretion and the induced change in supine blood pressure (P less than .05) with a blood pressure reduction in subjects with a low pretreatment urinary excretion of magnesium, and a pressor effect in the subjects with the highest pretreatment levels of urinary magnesium. The induced change in blood pressure was furthermore found to be inversely correlated to the changes in serum magnesium and urinary excretion of sodium (P less than .03) induced by treatment indicating that both a direct calcium antagonist action of magnesium at the cellular level as well as a diuretic effect of the increased magnesium load might be involved in the blood pressure effects of magnesium. Pretreatment serum potassium concentration also appeared to be a predictor of the induced change in standing blood pressure (P less than .03). In conclusion, magnesium supplementation does not seem to be effective in unselected mild hypertensive subjects or in subjects with a high-normal blood pressure and can therefore not be generally recommended.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1981

Formation of magnesium-phosphoenzyme and magnesium-calcium-phosphoenzyme in the phosphorylation of adenosine triphosphatase by orthophosphate in sarcoplasmic reticulum. Models of a reaction sequence.

The aim of the present study was to test simple reaction sequences which describe calcium-independent plus calcium-dependent phosphorylation of sarcoplasmic reticulum transport. ATPase by orthophosphate including the function of magnesium in phosphoenzyme formation. The reaction schemes considered were based on the reaction sequence for calcium-independent phosphorylation proposed previously; namely that the transport enzyme (E) forms a ternary complex (Mg . E . Pi), by random binding of free magnesium and free orthophosphate, which is in equilibrium with the magnesium-phosphoenzyme (Mg . E-P). Phosphorylation, performed at pH 7.0 20 degrees C and a constant free orthophosphate concentration using sarcoplasmic reticulum vesicles either unloaded or loaded passively with calcium in the presence of 5 mM or 40 mM CaCl2, resulted in a gradual decrease in the apparent magnesium half-saturation constant and an increase in maximum phosphoprotein formation with increasing calcium loads. When phosphorylation of sarcoplasmic reticulum vesicles preloaded in the presence of 5 mM CaCl2 was performed at a constant free magnesium concentration, a decrease in the apparent orthophosphate half-saturation constant and an increase in maximum phosphoprotein formation was observed as compared with vesicles from which calcium inside has been removed by ionophore X-537A plus EGTA treatment; however, both parameters remained unchanged by increasing free magnesium from 20 mM to 30 mM. When phosphorylation of sarcoplasmic reticulum vesicles passively loaded with calcium in the presence of 40 mM CaCl2, at which the saturation of the low-affinity calcium binding sites of the ATPase is presumably near maximum, was performed at increasing concentrations of free orthophosphate, there was a parallel shift of phosphoprotein formation as a function of free magnesium and vice versa, with no change in the maximum phosphoenzyme formation. Comparison of the experimental data with the pattern of phosphoprotein formation predicted from model equations for various theoretical possible reaction sequences suggests that phosphoenzyme formation from orthophosphate possesses the following features. Firstly, calcium present at the inside of the sarcoplasmic reticulum membrane binds to the free enzyme and in sequential order to E . Mg . Pi or Mg . E-P or to both, but neither to E. Mg nor to E . Pi. Secondly, calcium-independent and calcium-dependent phosphoproteins are magnesium-phosphoenzymes. Calcium-dependent phosphoenzyme is a magnesium-calcium-enzyme phosphate complex with 1 magnesium, 2 calciums and 1 orthophosphate (the last covalently) bound to the enzyme [Mg . E-P . (Cai)2], and not a 'calcium-phosphoprotein' without bound magnesium.

Adenosine Triphosphatases↗
PubMed1984

Magnesium studies in hemodialysis patients before and after treatment with low dialysate magnesium.

The magnesium status of 22 hemodialysis patients was studied by analyses of serum, skeletal muscle and peripheral blood lymphocyte levels of magnesium. Despite elevated serum magnesium, normal magnesium levels were noted in skeletal muscle and lymphocytes. 12 patients were exposed to a low dialysate magnesium concentration, resulting in normalization of serum magnesium but no changes in muscle or lymphocyte magnesium, which might indicate slow exchange between these intracellular stores and the extracellular fluid. Normalization of serum magnesium was followed by a slight rise in circulating parathyroid hormone levels without noticeable changes in serum calcium or phosphate levels. Since signs of an absolute magnesium excess were not detected, a combination of low dialysate magnesium and the use of an oral magnesium compound as a phosphate binder might be a way to decrease aluminium exposition in hemodialysis patients.

Alkaline Phosphatase↗
PubMed2003

The effects of magnesium prime solution on magnesium levels and potassium loss in open heart surgery.

UNLABELLED: In this study, we examined the effects of magnesium supplementation in the cardiopulmonary bypass (CPB) prime solution on pediatric patients' magnesium levels and potassium loss with open heart surgery. Forty pediatric patients undergoing heart surgery were randomly assigned either magnesium sulfate (magnesium group, n = 20; 0.25 mmol/kg) or saline (placebo group; n = 20) supplementation to the prime solution. Ionized magnesium (IMg) and urinary magnesium and potassium were measured at defined time points during and after CPB. In the magnesium group, IMg concentration was larger during CPB but not after CPB. IMg decreased in the early stages of CPB in the placebo group and decreased to an even smaller level 24 h after CPB. Urinary magnesium levels in the magnesium group were larger than those in the placebo group during and after CPB, and urinary potassium concentrations reached significantly smaller levels 24 h after CPB (44.2 +/- 2.9 versus 60.9 +/- 2.6 mmol/L; P < 0.01). We conclude that the addition of magnesium into prime solution maintains normal IMg levels and prevents potassium flux during the perioperative period. IMPLICATIONS: In our study, we demonstrate that a magnesium prime solution can prevent hypomagnesemia during and after cardiopulmonary bypass (CPB) and decrease the urinary potassium loss after CPB in pediatric patients undergoing open heart surgery.

Cardiac Surgical Procedures↗
PubMed1990

Effects of temperature, and dietary magnesium and nickel levels on magnesium and nickel concentrations during the moult-cycle in Oniscus asellus (Porcellionidae, Isopoda, Crustacea).

Mean magnesium concentrations in intermoult Oniscus asellus, caged at 20 degrees C for 10 days, ranged from 1,059.15 +/- 51.9 ppm on diets containing 10 ppm nickel, to 6,827.6 +/- 314.1 ppm on a mixture of 500 ppm magnesium + 10 ppm nickel. Mean nickel concentrations ranged from 89.4 +/- 4.3 ppm on diets containing 500 ppm magnesium, to 314.0 +/- 14.8 ppm on a mixture of 500 ppm magnesium + 10 ppm nickel. At 30 degrees C, magnesium tissue concentrations ranged from 4,149.8 +/- 153.5 ppm on diets with 10 ppm nickel to 12,602.6 +/- 529.3 ppm on 500 ppm magnesium. Nickel concentrations at 30 degrees C varied from 156.8 +/- 6.7 in isopods in the control to 490.5 +/- 23.5 ppm on those on 500 ppm magnesium + 10 ppm nickel. Magnesium in intermoult isopods was mainly stored in other tissues, including the exoskeleton, and nickel in the hepatopancreas. Differences in both magnesium and nickel concentrations between males and females were not significant. Magnesium and nickel concentrations in postmoult isopods, on the average, amounted to 367.6 +/- 16.5 ppm and 18.7 +/- 0.7 ppm, respectively, at 20 degrees C, and 369.9 +/- 16.3 ppm and 30.9 +/- 1.3 ppm, respectively, at 30 degrees C. Differences between males and females, and between various treatments were not significant at P greater than 0.01. It is suggested that both hepatopancreas and other tissues, including the exoskeleton, are used as sinks to get rid of excessive tissue magnesium and nickel during the moult-cycle.

Animals↗
PubMed2002

[Level of total and ionized magnesium fraction based on biochemical analysis of blood and hair and effect of supplemented magnesium (Slow Mag B6) on selected parameters in hypertension of patients treated with various groups of drugs].

The aim of this work was to determine the concentration of total and ionized magnesium in hair and blood of patients with primary hypertension and the influence of oral magnesium supplementation (Slow-Mag B6) on clinical parameters and blood pressure values. 92 patients were recruited from the Family Care Unit, Pomeranian Academy of Medicine in Szczecin. Each patient was treated during at least 6 months preceding the study with a single antihypertensive agent from one of the following groups: ACE inhibitors, beta-receptor inhibitors, Ca channel blockers, diuretics. The control group included patients with hypertension not treated pharmacologically. Changes in ionized magnesium concentration before and after oral magnesium supplementation were studied in relation to total cholesterol, triglycerides, and other parameters of importance in hypertension. Significantly lower total magnesium concentrations were demonstrated in hair of patients receiving ACE inhibitors and diuretics in comparison to controls. Ionized magnesium concentrations in serum of hypertensive patients were significantly reduced as compared with controls. A highly significant increase in these levels was noted after magnesium supplementation. Blood pressure values after magnesium supplementation were reduced in the study group by an average of 15-20 mmHg for systolic and 5-9 mmHg for diastolic blood pressure. Correlations between ionized magnesium and triglyceride concentrations in patients treated with Ca channel blockers before oral Mg supplementation were found. Patients treated with diuretics demonstrated correlations between total magnesium and total cholesterol concentrations. Following oral magnesium supplementation with Slow-Mag B6 at 320 mg/day, the frequency of complaints reported by patients, including irregular heart beat, pricking heart pain, nervousness, sleep disorders, irritability/tearfulness was reduced. There was no effect on other complaints, such as mental and physical fatigue, constipation/diarrhea, and anxiety.

Administration, Oral↗
PubMed1992

Magnesium and obesity: influence of gender, glucose tolerance, and body fat distribution on circulating magnesium concentrations.

Obesity is characterized by a high risk for glucose intolerance and cardiovascular disease. Since magnesium deficiency or depletion have often been associated with both pathologies, is of interest to study magnesium status in severely obese subjects before any form of treatment. Negative magnesium balances have been described in overweight persons submitted to total starvation, hypocaloric diets, and obesity surgery. For this reason 80 non-diabetic obese men and 118 age-matched obese women were studied. Serum and erythrocyte magnesium concentrations were significantly higher in the male population but the mean values were not suggestive of a magnesium deficit before any form of treatment was started. Since metabolic abnormalities and cardiovascular risk are greater in patients with upper body fat distribution (UBFD) both sexes were subdivided according to "waist-to-hip" circumference ratio. No difference could be shown in the obese men but in women, UBFD subjects showed higher basal insulin levels and increased erythrocyte magnesium concentration as compared to those with classical gynoid fat distribution. A 75 g oral glucose tolerance test enabled the subjects to be subdivided into those with normal or impaired glucose tolerance (IGT). The IGT group in both sexes was older and more obese. Mean values of serum magnesium and erythrocyte magnesium were not decreased despite the more pronounced insulin resistance in the IGT group. However a significant negative correlation was found between fasting blood sugar/insulinaemia and erythrocyte magnesium, showing that this middle-aged obese population can maintain normal circulating levels of magnesium, in contrast to type II diabetics or older subjects where for other reasons (urinary losses or decreased intake) magnesium status is interfered with.

Adipose Tissue↗
PubMed1987

Variable response of serum magnesium and total cholesterol to different magnesium intakes and exercise levels in rats.

Thirty-two Sprague-Dawley rats were divided into four groups: control, exercise, low-magnesium diet, and a combination of low-magnesium diet and exercise. The low-magnesium diet contained 80 ppm of magnesium and the exercise consisted of 1-hour swim sessions, 5 days per week for 4 weeks. Serum magnesium was depressed and total cholesterol was elevated (p less than 0.05) in the low-magnesium diet, sedentary animals as compared to both sedentary and exercised rats fed a normal magnesium diet. The group on the combination of hypomagnesemic diet and exercise was not statistically different from the normal-diet group. It is concluded that exercise favorably affects the serum magnesium and cholesterol responses induced by a hypomagnesemic diet. There may be a threshold serum magnesium level to elicit the elevated cholesterol response, or other metabolic factors affected by exercise may modify the expected cholesterol response associated with deprivation or severe deficiency of dietary magnesium and related serum magnesium levels.

Animals↗
PubMed1997

[Magnesium deficiency and magnesium substitution. Effect on ventricular cardiac arrhythmias of various etiology].

During recent years there has been an increasing but still controversial discussion on the antiarrhythmic effects and overall benefit of magnesium when directed to patients with various types of ventricular tachyarrhythmias. While magnesium is considered to be a simple, safe and cost-effective approach and many casuistic and empiric reports have indicated antiarrhythmic properties of magnesium in patients with suspected or manifest ventricular arrhythmias, controlled studies proving the antiarrhythmic and overall benefit and justifying a broader use of magnesium in treating various types of ventricular arrhythmias are missing or rare. At present, antiarrhythmic properties and clinical benefit of magnesium application has only been established in patients with torsade de pointes and digitalis-induced ventricular tachyarrhythmias. In perioperative patients at risk for ventricular tachyarrhythmias and in patients suffering from manifest heart failure, data may also indicate some antiarrhythmic properties of magnesium, however, in this case with a wide consensus that the prevention of magnesium deficit is more effective and preferred in most patients over the therapeutic application of magnesium. Another group of patients who may profit from such a therapeutic approach are patients with frequent ventricular arrhythmias and stable underlying heart disease, in whom a recently published double-blind, randomized study documented an antiarrhythmic effect of a 3 week treatment with potassium and magnesium. For all other types of ventricular tachyarrhythmias, the therapeutic use of magnesium can be considered as not harmful, but also as not proven to be effective.

Anti-Arrhythmia Agents↗