Renal handling of magnesium in the dog

Sg, Massry; Jw, Coburn

doi:10.1152/ajplegacy.1969.216.6.1460

Cited by 81 publications

(33 citation statements)

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“…In the dog, Massry et al (24) were unable to show tubular secretion of magnesium although others found that urinary magnesium may reach values that are 10-20% greater than filtered magnesium durinig the concomitant admipistration of magnesium salts, saline, and furosemide (34). It appears that if magnesium secretion by the nephron exists, it plays a minor role in the renal handling of magnesium.…”

Section: Discussionmentioning

confidence: 99%

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Effect of Phosphate Depletion on Magnesium Homeostasis in Rats

Kreußer¹,

Kurokawa²,

Aznar³

et al. 1978

J. Clin. Invest.

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A B S T R A C T The effects of phosphate depletion on magniesiumni (NMg) homeostasis were evaluated in rats fed a diet containing 0.03% phosphorus for periods up to 8 wk. Plasma phosphorus fell signiificantly (P < 0.01) from 10.1+0.27 (SE) to 5.0±0.54 mgIl00 ml within 1 day and conitiniued to fall gradually to a level of 1.2±0.21 mg/100 ml by the end of the 8th wk. A signiificant (P < 0.01) increment in urinary Mg excretion (UMgV) from 46±2.7 to 126±24 ,ueq/24 h occurred during the 1st day of phosphate depletion; UMgV reached a peak of 300±+24 pieq/24 h by the 3rd day and remained high ranging between 150-300 ,ueq/24 h, thereafter. The magnittude of the magnesuria was related to the degree of hypophosphatemia and was not affected by lowering the calcium intake and reducing the hypercalciuria. The concentration of plasma Mg fell significantly (P < 0.01) from 1.2±0.02 to 0.79±0.10 meq/liter by the 1st day of the study and remained low throughout.Mg balance became negative during the 1st day of phosphate depletion and remained so during the entire study. This occurred despite a significant increment in the fraction of ingested Mg absorbed which becarmie evident by the 3rd wk of phosphate depletion. Mg contenit of muscle, kidney, and liver were not affected but bone Mg was reduced significantly. The change in bone Mg was not due to an overall reduction in bone mineral contenit because bone calcium content was not affected. Supplementation of large amounts of Mg (800-1,000 ,ueq/day) in the drinking water produced a normalization of serum Mg but did not bring about restoration of bone Mg despite a positive Mg balance. The disturbances in Mg metabolism were independent of the age or veight of the animals.Our results indicate that phosphate depletion is Dr. Kreusser is a Fellow of the Deutsche Forschungsgemeinschaft.Dr. Aznar is a Fellow of the Del Amo Foundation.

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Section: Discussionmentioning

confidence: 99%

“…Fourth, PD has been reported to cause hypofunction of the parathyoid glands (12,22) and because parathyroid hormone (PTH) enhances magnesium reabsorption (23,24), partial or complete lack of PTH could cause modest magnesuria. However, the data of Cuisinier-Gleizes et al (7) argues against this possibility.…”

Section: Discussionmentioning

confidence: 99%

Effect of Phosphate Depletion on Magnesium Homeostasis in Rats

Kreußer¹,

Kurokawa²,

Aznar³

et al. 1978

J. Clin. Invest.

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“…In a few instances, the percentage of filtered sodium excreted was increased during phosphate depletion; however, this change was of a small magnitude and the simultaneous augmentation in calcium excretion was disproportionately greater. Second, urinary calcium also increases with the augmented magnesium excretion caused by magnesium loading (17)(18)(19)(20). In the studies carried out in humans by Lotz et al (1), phosphate depletion was induced using magnesium-aluminum-hy- Control indicates the mean of 3-4 periods collected before the injection of parathyroid extract and PTE indicates the mean of 3-4 periods collected after the intramuscular injection of Lilly parathyroid extract, 100 U each hour X 3.…”

Section: Discussionmentioning

confidence: 99%

“…Each 100 g mineral mixture contains: NaCl monal or nonhormonal factors affect the rate of urinary calcium excretion: an augmentation in sodium excretion, produced by volume expansion (11)(12)(13), osmotic agents (14), and various diuretics (14)(15)(16), is associated with calciuresis. Acute (17,18) and chronic (19,20) increases in urinary magnesium and an increment in the urinary excretion of complexing anions, such as citrate (21), sulphate (22), and gluconate (23), also augment the rate of calcium excretion. The administration of parathyroid extract enhances the renal tubular reabsorption of calcium (24)(25)(26)(27), and parathyroidectomy is followed by a rise in the renal clearance of calcium (24).…”

Section: Introductionmentioning

confidence: 99%

Changes in serum and urinary calcium during phosphate depletion: studies on mechanisms

Coburn¹,

Massry²

1970

J. Clin. Invest.

127

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ABSTRA CT The changes in serum calcium and the renal handling of this ion were evaluated during phosphate depletion. 96 renal clearance studies were carried out in 10 dogs before and after prolonged phosphate depletion (30-160 days) and after repletion. Depletion was produced by reducing phosphate intake and administering aluminum hydroxide gel while intakes of sodium, calcium, and magnesium were constant. With phosphate depletion, serum phosphorus fell to less than 1.0 mg/100 ml and diffusible serum calcium either remained unchanged or rose transiently. Glomerular filtration rate (GFR) fell by 15 to 53%. Despite the reduced filtered load of calcium, its fractional excretion increased in most experiments. This hypercalciuria was not dependent upon changes in sodium or magnesium excretion, or the urinary concentration of complexing anions, and persisted after sodium restriction. Phosphate repletion reversed the effects on GFR and calcium excretion. The intravenous infusion of small quantities of phosphate (0.04 mmole/min) into either intact or thyroparathyroidectomized (T-PTX), phosphate-depleted animals caused a significant reduction in fractional excretion of calcium, but the intrarenal infusion of 0.02 mmole/min of phosphate into one kidney failed to produce an ipsilateral effect. The administration of parathyroid extract reduced fractional calcium excretion, but the latter remained significantly elevated. After T-PTX, fractional calcium excretion did not increase in the phosphate-depleted animals. Furthermore, serum calcium was normal after T-PTX until serum phosphorus increased slightly, and

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“…The Ca 2+ /Mg 2+ -sensing receptor also explains the so-called "Tm" phenomenon of urinary magnesium excretion (101,(120)(121)(122). Clearance studies have suggested that renal magnesium reabsorption is a Tmlimited process, i.e.…”

Section: 2ca2+/mg2+-sensing:hypercalcemia Hypermagnesemiamentioning

confidence: 99%

Epithelial magnesium transport and regulation by the kidney

C²

2000

Front Biosci

102

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Magnesium is the fourth most abundant cation in the body and the second most common cation in the intracellular fluid. It is the kidney that provides the most sensitive control for magnesium balance. About a 80% of the total serum magnesium is ultrafilterable through the glomerular membrane. In all of the mammalian species studied to date, the proximal tubule of the adult animal reabsorbs only a small fraction, 10-15%, of the filtered magnesium. Unlike the adult proximal convoluted tubule that of young rats (aged 13-15 days) reabsorbs 50-60% of filtered magnesium along the proximal tubule together with sodium, calcium, and water. Micropuncture experiments, in every species studied to date, indicates that a large part (approximately 60%) of the filtered magnesium is reabsorbed in the loop of Henle. Magnesium reabsorption in the loop occurs within the cortical thick ascending limb (cTAL) by passive means driven by the transepithelial voltage through the paracellular pathway. Micropuncture experiments have clearly showed that the superficial distal tubule reabsorbs significant amounts of magnesium. Unlike the thick ascending limb of the loop of Henle, magnesium reabsorption in the distal tubule is transcellular and active in nature. Many hormones and nonhormonal factors influence renal magnesium reabsorption to variable extent in the cTAL and distal tubule. Moreover, nonhormonal factors may have important implications on hormonal controls of renal magnesium conservation. Dietary magnesium restriction leads to renal magnesium conservation with diminished urinary magnesium excretion. Adaptation of magnesium transport with dietary magnesium restriction occurs in both the cTAL and distal tubule. Elevation of plasma magnesium or calcium concentration inhibits magnesium and calcium reabsorption leading to hypermagnesiuria and hypercalciuria. The

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Renal handling of magnesium in the dog

Cited by 81 publications

References 0 publications

Effect of Phosphate Depletion on Magnesium Homeostasis in Rats

Effect of Phosphate Depletion on Magnesium Homeostasis in Rats

Changes in serum and urinary calcium during phosphate depletion: studies on mechanisms

Epithelial magnesium transport and regulation by the kidney

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