Magnesium reabsorption in the juxtamedullary loop of Henle: effect of magnesium deprivation

1987 ◽  
Vol 65 (9) ◽  
pp. 1918-1922 ◽  
Author(s):  
Denis R. Roy
Keyword(s):  
Magnesium Deficiency ◽  
Magnesium Concentration ◽  
Control Group ◽  
Loop Of Henle ◽  
Two Phase ◽  
Daily Excretion ◽  
Tightly Coupled ◽  
Magnesium Excretion ◽  
Plasma Magnesium ◽  
Filtered Load

To determine the contribution of the juxtamedullary loop of Henle to magnesium reabsorption during magnesium deficiency, we performed two-phase micropuncture studies of end-descending limbs in a group of magnesium-deficient rats (n = 7) and in a pair-fed control group (n = 8) given MgCl2 in their drinking water. In the magnesium-deficient rats, daily excretion of magnesium fell to very low values (1.2 ± 0.2 vs. 52 ± 12 μM∙day−1∙100 g body weight−1, p < 0.05). Plasma magnesium concentration and fractional magnesium excretion during the control phase were nearly 52 and 27%, respectively, of the values observed in pair-fed controls. Fractional magnesium delivery to the end-descending limb did not differ significantly between the two groups. During the acute magnesium repletion phase, fractional magnesium excretion and fractional magnesium delivery to the end-descending limb increased by a similar value in the two groups of rats, despite a lower filtered load of magnesium in the magnesium-deficient group. Absolute magnesium reabsorption upstream to the end-descending limb was lower in the magnesium-deficient rats but was otherwise tightly coupled to the filtered load of magnesium (Y = 0.91 + 0.37 x, r = 0.82, p < 0.05). Similar observations were made with regards to whole kidney magnesium reabsoiption. Our results suggest that, in young magnesium-deficient rats, magnesium reabsorption is tightly coupled to the filtered load of magnesium both in segments upstream to the juxtamedullary end-descending limb and in the whole kidney, and that a reabsorptive defect for magnesium is not evident in this setting.

Early adaptation of renal magnesium reabsorption in response to magnesium restriction

1989 ◽  
Vol 257 (6) ◽  
pp. F974-F977 ◽  
Author(s):  
I. M. Shafik ◽  
G. A. Quamme
Keyword(s):  
Plasma Concentration ◽  
Magnesium Concentration ◽  
Loop Of Henle ◽  
Cellular Adaptation ◽  
Magnesium Transport ◽  
Low Magnesium ◽  
Dietary Magnesium ◽  
Magnesium Excretion ◽  
Plasma Magnesium ◽  
Filtered Load

Dietary magnesium restriction with hypomagnesia is normally associated with diminished urinary magnesium excretion. Young rats were pair fed control magnesium diets (0.05% MgSO4) and magnesium-restricted diets (less than 0.01% Mg), and tubular magnesium reabsorption was assessed to determine the importance of filtered load (plasma magnesium) and to establish the presence of cellular adaptation of magnesium transport. Urinary magnesium excretion decreased from 17.2 +/- 2.7 to 5.9 +/- 1.2% over 20 h on low-magnesium diets without a change in plasma concentration (0.61 +/- 0.02 mM). This cellular adaptation was rapid (within 5 h), specific (without effect on sodium and calcium), and sensitive (without change in plasma concentration). Micropuncture studies demonstrated that cellular adaptation occurred within the loop of Henle. After 20 h, plasma magnesium fell with an associated further decrease in fractional magnesium excretion. Accordingly, cellular adaptation of magnesium transport occurs with magnesium-deficient diets, and alterations in filtered magnesium and plasma magnesium concentration are not necessary for magnesium conservation.

scholarly journals Association between serum magnesium and obesity in postmenopausal women

2018 ◽  
Vol 6 (9) ◽  
pp. 3156
Author(s):  
Alka Yadav ◽  
Madhuri Gupta ◽  
R. C. Gupta
Keyword(s):  
Postmenopausal Women ◽  
Magnesium Deficiency ◽  
Serum Magnesium ◽  
Venous Blood ◽  
Cross Sectional Study ◽  
Magnesium Concentration ◽  
Control Group ◽  
Excess Body Weight ◽  
Cross Sectional ◽  
Dietary History

Background: Obesity is a complex, multifactorial condition in which excess body weight may put a female at risk of serious health problems such as hypertension, dyslipidemia, diabetes mellitus and cardiovascular diseases. Magnesium deficiency is reported to be associated with obesity in children and adolescents. An inverse relationship has been reported between serum magnesium and estrogen levels in women. It is not known whether magnesium deficiency may have a role in genesis of obesity in women after menopause. Therefore, the present study was planned to compare serum magnesium levels in obese and non-obese postmenopausal women and to find out the relationship, if any, between serum magnesium levels and obesity.Methods: This cross-sectional study was conducted in the department of Biochemistry at National Institute of Medical Sciences and Research, Jaipur, Rajasthan on fifty subjects over a period of six months. Twenty-five obese postmenopausal women (BMI ≥ 30) having their final menstrual period at least one year prior to the study were taken as the study group and twenty-five non-obese (BMI ≤ 22.9) post-menopausal women were taken as control group. All subjects were asked to give detailed dietary history using Food Frequency Questionnaire (FFQ). Venous blood samples were collected after an overnight fast for estimation of serum total magnesium in all subjects.Results: Obese postmenopausal women had significantly higher weight (78.36±0.064kg) and BMI (32.68±1.7kg/mt2) compared to non-obese postmenopausal women (wt. 54.72±4.80kg and BMI 21.75±1.68kg/mt2). The mean±SD serum magnesium concentration found in the obese postmenopausal women was 1.40±0.45mg/dl as compared to 2.03±0.49 mg/dl in the non-obese group. Pearson’s correlation analysis showed a significant (r = -0.9) negative correlation between BMI and serum magnesium in postmenopausal women.Conclusions: Serum magnesium was lower in obese postmenopausal women as compared to that in non-obese postmenopausal women. Serum magnesium was negatively correlated with BMI. Magnesium supplementation may be useful in prevention of obesity after menopause.

Effect of magnesium loading on magnesium delivery to the juxtamedullary end-descending limb

1985 ◽  
Vol 248 (1) ◽  
pp. F145-F151
Author(s):  
D. R. Roy
Keyword(s):  
Flow Rate ◽  
Magnesium Concentration ◽  
Group 4 ◽  
Intravenous Magnesium ◽  
Group 3 ◽  
Group 2 ◽  
Magnesium Excretion ◽  
Plasma Magnesium ◽  
Normal Controls ◽  
Group 1

Previous micropuncture and microperfusion studies in acutely hypermagnesemic rats have yielded conflicting results with respect to magnesium transport in Henle's loop. The following experiments were performed to reexamine, by micropuncture of papillary end-descending limb, whether magnesium undergoes intratubular secretion in magnesium-loaded rats. Group 1 animals served as normal controls; group 2 animals received an acute intravenous magnesium load; group 3 animals were orally magnesium loaded for 3 wk before receiving an acute intravenous magnesium load during micropuncture; group 4 animals were acutely thyroparathyroidectomized and water loaded before receiving an acute magnesium load. Fractional magnesium delivery to the end-descending limb did not differ from the corresponding value observed in the superficial proximal tubule in normal animals (67 +/- 5.3 vs. 76 +/- 7.6%). Acute magnesium loading raised plasma magnesium concentration and fractional magnesium excretion more than twofold but did not change fractional magnesium delivery to the end-descending limb or superficial nephron significantly from control values (75 and 73%). Chronic oral magnesium loading raised daily urinary magnesium excretion threefold (183 vs. 53 mumol X day-1 X 100 g body wt-1, P less than 0.05), but acute magnesium loading in this group did not significantly alter fractional delivery to the end-descending limb (85 +/- 10%, NS). Increasing intratubular flow rate while acutely raising plasma magnesium concentration (group 4) also did not induce intratubular magnesium secretion. The absence of significant changes in fractional magnesium delivery to the end-descending limb during magnesium loading suggests that intratubular magnesium secretion, if at all present, is very small and of questionable significance.

Cyclosporin-induced hypomagnesaemia and renal magnesium wasting in rats

1988 ◽  
Vol 75 (5) ◽  
pp. 509-514 ◽  
Author(s):  
Norman L. M. Wong ◽  
John H. Dirks
Keyword(s):  
Magnesium Chloride ◽  
Magnesium Concentration ◽  
Group Iii ◽  
Cyclosporin Treatment ◽  
Group I ◽  
Three Phase ◽  
Group Ii ◽  
Renal Magnesium Wasting ◽  
Magnesium Excretion ◽  
Plasma Magnesium

1. Twenty-four hour clearance studies were performed on three groups of rats to determine the hypomagnesaemic effect of cyclosporin. Group I rats served as controls, whereas group II rats received 10 mg of cyclosporin/kg and group III rats received 20 mg of cyclosporin/kg daily. 2. After 7 days of cyclosporin treatment, plasma magnesium concentration was 1.04 ±0.01 mmol/l in control rats compared with 0.85 ±0.01 mmol/l in group II and 0.81 ±0.02 mmol/l in group III. After 14 days of cyclosporin administration, group III rats developed severe hypomagnesaemia (0.67 ± 0.01 mmol/l). This reduction in plasma magnesium was associated with an increase in the urinary excretion of magnesium. 3. This reduction in plasma magnesium and increment in magnesium excretion returned to normal 7 days after cessation of treatment. 4. Additional three-phase acute clearance experiments were performed on eight normal and 12 cyclosporin-treated rats (20 mg/kg). These animals were subjected to acute magnesium chloride infusion. After graded magnesium chloride infusion, despite a similar rise in plasma magnesium, the fractional magnesium excretion was significantly higher in the cyclosporin-treated animals. 5. Analysis of the fractional intestinal absorption of magnesium suggested that the development of hypomagnesaemia after cyclosporin treatment is due to magnesium loss by the kidney. Furthermore, this effect of cyclosporin on magnesium transport is only present during cyclosporin treatment and is reversible when treatment with cyclosporin is withdrawn.

RELATIONSHIP BETWEEN THE THYROID HORMONE AND MINERAL METABOLISM IN THE RAT

1972 ◽  
Vol 53 (1) ◽  
pp. 113-123 ◽  
Author(s):  
H. P. HUMPHRAY ◽  
F. W. HEATON
Keyword(s):  
Thyroid Hormone ◽  
Soft Tissues ◽  
Magnesium Deficiency ◽  
Mineral Metabolism ◽  
Dry Weight ◽  
Magnesium Concentration ◽  
Thyroid Activity ◽  
Close Relationship ◽  
Adolescent Rats ◽  
Plasma Magnesium

SUMMARY The effect of thyroid activity on the distribution of magnesium, potassium and calcium between plasma, soft tissues and bone was investigated in adolescent rats. Administration of thyroxine or propylthiouracil produced variable effects on their concentrations in tissues, but the total amounts of all three metals in the complete liver and a single femur showed consistent changes that were similar to changes in the nitrogen content of the liver and the dry weight of bone. It is concluded that the influence of thyroid hormone on mineral metabolism is secondary to its action on tissue anabolism and catabolism. Magnesium deficiency decreased thyroid activity, and loading with magnesium salts increased the activity of the gland, a very close relationship being observed between the plasma magnesium concentration and the activity of the thyroid. Deficiency or loading with potassium salts produced changes that were qualitatively similar to those with magnesium, but less well-defined, and it appears that potassium may have an indirect effect on the gland. A hypothesis is advanced to explain how, in the absence of a homeostatic relationship, the availability of magnesium could modulate thyroid activity.

Magnesium Metabolism in Patients on Regular Dialysis Treatment

1971 ◽  
Vol 41 (2) ◽  
pp. 131-139 ◽  
Author(s):  
P. Schmidt ◽  
R. Kotzaurek ◽  
J. Zazgornik ◽  
Herta Hysek
Keyword(s):  
Magnesium Deficiency ◽  
Significant Rise ◽  
Magnesium Concentration ◽  
Dialysis Fluid ◽  
Dialysis Treatment ◽  
Magnesium Metabolism ◽  
Bath Solution ◽  
Regular Dialysis Treatment ◽  
High Concentrations ◽  
Plasma Magnesium

1. In eight patients being treated by chronic dialysis the relation of magnesium metabolism to the magnesium concentration of the dialysate was investigated. During four periods of 2–6 weeks the magnesium concentrations of the dialysis fluid were 0.44±0.15 mg/100 ml, 0.70±0.24 mg/100 ml, 1.83±0.18 mg/100 ml and 1.97±0.21 mg/100 ml. 2. During all periods the concentration of plasma magnesium and ultrafiltrable magnesium was above normal. The concentration of erythrocyte magnesium was below normal with the lowest concentration in the bath, while all other dialysate concentrations yielded readings above normal values. 3. During dialysis the concentration of plasma magnesium and ultrafiltrable magnesium dropped only during the periods with low concentrations of magnesium in the dialysate. During dialysis with the lowest concentration the values for erythrocyte magnesium showed a significant rise whereas with high concentrations the concentration fell significantly. The changes in erythrocyte magnesium proved to be independent of the calcium content of the dialysis fluid. 4. The maximum loss of magnesium to the bath solution amounted to 710 mg, with the magnesium content of the bath being only 0.27 mg/100 ml. The net transfer of magnesium to the blood of the patient amounted to 102 mg with a dialysate magnesium concentration of 1.86 mg/100 ml. 5. It is concluded that low dialysate magnesium concentrations result in erythrocyte magnesium deficiency whereas high concentrations cause magnesium overloading. A magnesium concentration of 0.7 mg/100 ml is suggested for the bath solution used in regular dialysis treatment.

scholarly journals STANNIECTOMY INCREASES RENAL MAGNESIUM AND CALCIUM EXCRETION IN FRESHWATER NORTH AMERICAN EELS (ANGUILLA ROSTRATA)

1993 ◽  
Vol 181 (1) ◽  
pp. 107-118
Author(s):  
D. G. Butler
Keyword(s):  
North American ◽  
Calcium Concentration ◽  
Urinary Calcium ◽  
Plasma Calcium ◽  
Magnesium Concentration ◽  
Calcium Excretion ◽  
Plasma Calcium Concentration ◽  
Magnesium Excretion ◽  
Plasma Magnesium ◽  
American Eels

The corpuscles of Stannius are linked to the renal transport of magnesium in freshwater North American eels. The urinary magnesium concentration and rate of magnesium excretion increased 3 days after the corpuscles had been removed, a trend which continued throughout a 14 day observation period. There was no overall change in urine flow rates except for a brief 50 % reduction 2 days after stanniectomy. Plasma magnesium concentrations drifted downward after stanniectomy. In contrast, plasma calcium concentrations increased significantly within 2 days following stanniectomy and they continued to increase thereafter. Urinary calcium concentrations and the rate of urinary calcium excretion increased 7 days after stanniectomy, implying that the renal response was subject to the increase in plasma calcium concentration: the urine/plasma calcium ratio remained constant. Even though the urinary calcium concentration increased after stanniectomy, the increase in urinary magnesium concentration was proportionally greater.

Hypomagnesemia in Obese Subjects: Evidence of Systematic Review and Meta-analysis

2020 ◽  
Vol 16 (7) ◽  
pp. 1044-1051
Author(s):  
Kyria J.C. Cruz ◽  
Ana R.S. de Oliveira ◽  
Suelem T. de Freitas ◽  
Gilberto S. Henriques ◽  
Dilina do Nascimento Marreiro
Keyword(s):  
Systematic Review ◽  
Magnesium Deficiency ◽  
Meta Analysis ◽  
Case Control ◽  
Magnesium Concentration ◽  
Healthy Individuals ◽  
Case Control Studies ◽  
Nutritional Problem ◽  
Obese Subjects ◽  
Plasma Magnesium

Background:: Magnesium deficiency is a global nutritional problem which seems to influence obesity-associated metabolic disorders because magnesium plays an important role in the prevention and treatment of many diseases. Objective:: We conducted a systematic review and meta-analysis to evaluate the relationship between plasma magnesium concentrations and obesity. Methods:: A systematic review and meta-analysis of case-control studies was conducted. Relevant studies were identified from a literature search using electronic databases. Results:: Ten case-control studies were evaluated in this meta-analysis. Results demonstrated that obese individuals presented lower plasma magnesium concentration than healthy individuals (standardized mean difference [SMD] = -0.44, 95% confidence interval = -0.88 to -0.01). In subgroup analyses, there were differences in plasma magnesium concentration between obese and healthy individuals according to study location, gender, case age, control age, method for assessment of magnesium concentration and study quality. Furthermore, meta-regression analyses showed that the source of heterogeneity of magnesium levels among studies was control age. Conclusion:: Evidence of this systematic review and meta-analysis show hypomagnesemia in obese individuals of both genders.

scholarly journals Magnesium Supplementation Does Not Affect Blood Calcium Level in Treated Hypoparathyroid Patients

2012 ◽  
Vol 97 (11) ◽  
pp. E2090-E2092 ◽  
Author(s):  
Maire Lubi ◽  
Kaia Tammiksaar ◽  
Svetlana Matjus ◽  
Eero Vasar ◽  
Vallo Volke
Keyword(s):  
Calcium Level ◽  
Magnesium Deficiency ◽  
Plasma Calcium ◽  
Endocrine Disorders ◽  
Magnesium Supplementation ◽  
Two Phase ◽  
Blood Calcium ◽  
Clinically Significant ◽  
Plasma Magnesium ◽  
Magnesium Treatment

Context: Magnesium is involved in the homeostasis of calcium metabolism, and magnesium deficiency may lead to clinically significant hypocalcemia. We have had two cases in our department in which treated hypoparathyroid patients with stable calcium levels developed hypercalcemia in conjunction with supplementary magnesium use. To our knowledge, there has been no prospective study looking at the effect of supplementary magnesium on calcium homeostasis in hypoparathyroid patients. Objective: The aim of this pilot study was to evaluate whether magnesium treatment affects plasma calcium levels in hypoparathyroid patients. Design and Setting: We conducted a prospective, two-phase, uncontrolled treatment trial at a referral center of endocrine disorders. Participants: We enrolled treated (calcium + vitamin D analog) hypoparathyroid patients with normal plasma magnesium levels. Intervention: Three weeks of treatment with oral magnesium (350 mg/d) were followed by 2 wk off treatment. Measures: We compared the plasma ionized calcium level after 3 wk of treatment to the pretreatment value. Plasma calcium, phosphate, magnesium, and creatinine levels were measured before treatment, after 3 wk on magnesium, and 2 wk after stopping magnesium treatment. Results: Ten patients completed the trial. Supplementary treatment with magnesium for 3 wk did not change calcium levels in these patients. Magnesium supplementation induced a small but statistically significant increase in the plasma magnesium level, but levels of phosphate and creatinine remained stable. Conclusions: Magnesium supplementation did not influence plasma calcium levels in treated hypoparathyroid patients.

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