Effect of a Magnesium-Deficient Diet on Magnesium Metabolism in Rabbits: A Study with Mg28

Aikawa, Jerry K.; Reardon, Jacqueline Z.; Harms, Dale R.

doi:10.1093/jn/76.1.90

Cited by 11 publications

(2 citation statements)

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“…Hypomagnesemia has been regularly associated with decreased alkaline phosphatase and inorganic pyrophosphatase activity in serum in rats (17)(18)(19)(20). However, depletion of intracellular magnesium and of the activities of alkaline phosphatase and inorganic pyrophosphatase, even in the presence of profound hypomagnesemia, is tissue specific, affecting chiefly bone and lung (19)(20)(21)(22).…”

Section: Discussionmentioning

confidence: 99%

Clearance of calcium pyrophosphate dihydrate crystals in vivo

McCarty

Palmer

James

1979

Arthritis & Rheumatism

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The clearance rate of isotopically labeled synthetic triclinic calcium pyrophosphate dihydrate (CPPD) crystals injected into rabbit joints was estimated by serial counting. Kinetic analysis using a four compartment model showed that half of the injected dose was cleared from 4 rabbit knee joints in 19.1 f 0.42 (SEM) days. Profound hypomagnesemia, produced in 2 rabbits with a low magnesium diet, did not affect the rate of crystal clearance detectably. Lavage of joints with solutions known to promote CPPD crystal solubility failed to remove detectable radioactivity. The previous finding of CPPD crystals in synovial phagocytes by electron microscopy, together with the finding of nuclide activity in the synovium and the failure to remove such activity by joint lavage, suggests that endocytosis by synovial cells is an important, effective mechanism controlling the synovial fluid concentration of crystals in patients with CPPD crystal deposition disease.We have previously shown that synthetic triclinic calcium pyrophosphate dihydrate crystals (CPPD) labeled with '@Yb are cleared from normal rabbit joints and arthritic human joints (1). These studies were undertaken to provide a theoretical framework that might lead to a rational means of CPPD removal from joints of afflicted patients; such treatment would be analogous to the highly successful therapies that effectively lead to the dissolution of monosodium urate crystals from the tissues of gouty patients. Clearance of one half of the injected dose of I6'Yb CPPD triclinic crystals, 10-20 p in greatest dimension, the dominant crystal species in CPPD crystal deposition disease, ranged from 32 to 99 days in human knee joints. The rate of clearance from rabbit joints was clearly dependent on crystal size (1). Half of an injected dose of crystals sized 10-20 p was cleared in 7 and 12 days from the synovium of 2 rabbits. The "half clearance time" of crystals sized 20-50 p required 16 days, whereas that of a dose of crystals greater than 50 p in size took 84 days.Each observed clearance of I6'Yb CPPD, as measured by serial gamma counting over an injected joint, was corrected by the kinetic behavior of free 16'Yb injected into the same (human) or contralateral (rabbit) joint. The kinetic analysis used to calculate the rate of crystal clearance required the assumption that free 169Yb and 16'Yb released from labeled crystals were handled identically by the synovial tissues. The present series of experiments examined clearance of synthetic triclinic CPPD labeled with both 'Ta and 85Sr from rabbit joints, a technique relatively independent of the in vivo kinetics of free isotope. MATERIALS AND METHODSPreparation and characterization of labeled crystals. Triclinic CPPD were prepared as previously outlined (1) except that ''Ca (22.6 pCi/pg) from Amersham-Searle and '?ST

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Section: Discussionmentioning

confidence: 99%

Clearance of calcium pyrophosphate dihydrate crystals in vivo

McCarty

Palmer

James

1979

Arthritis & Rheumatism

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“…When zsMg became available several years ago, we made a preliminary study of the dynamics of magnesium transfer in the tissues of rabbits maintained on a Mg-deficient diet for 30 days. 3 The results of this study are reviewed in the present report, which also describes subsequent studies made in rabbits maintained on a diet extremely low in magnesium for four to six weeks. In addition to studying changes in blood constituents in such animals, we have done some preliminary in vitro studies on the intestinal transfer of magnesium in Mg-deficient and normal rabbits.…”

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confidence: 94%

²⁸Mg STUDIES IN MAGNESIUM‐DEFICIENT ANIMALS

Aikawa¹,

David²

1969

Annals of the New York Academy of Sciences

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The first investigators to succeed in producing magnesium (Mg) deficiency experimentally were Orent and his coworkers,' who reported in 1934 that the rats used for their study showed a depletion of bone magnesium. Subsequent investigators2 have reported that the soft-tissue content of magnesium is not appreciably altered even in severe deficiency. When zsMg became available several years ago, we made a preliminary study of the dynamics of magnesium transfer in the tissues of rabbits maintained on a Mg-deficient diet for 30 days.3 The results of this study are reviewed in the present report, which also describes subsequent studies made in rabbits maintained on a diet extremely low in magnesium for four to six weeks. In addition to studying changes in blood constituents in such animals, we have done some preliminary in vitro studies on the intestinal transfer of magnesium in Mg-deficient and normal rabbits. THE EXTERNAL BALANCE AND Mg, STUDY Material and MethodsAdult male domestic rabbits were placed in individual stainless steel metabolism cages and were given unrestricted quantities of tap water containing 0.6 milliequivalent (mEq) of magnesium per liter. The basal diet used for rats by Mackenzie and Mackenzie4 was supplemented by the salt mixture of Hubbell and his coworkers,5 except that the magnesium salts were omitted. The composition of this diet, which contains 6.6 mEq of magnesium per kilogram, has been described previously.The z8 Mg was received as MgCI2 in concentrated HCI; the specific activity was on the order of 8-10 pc/mEq. The concentration of magnesium in the solution injected was 0.4 mEq/ml, and each injection contained 2 mEq.The procedures for collecting the samples for the external balance study, for measuring the exchangeable magnesium content ( Mge), and for assaying radioactivity have been described previ~usly.~ The magnesium concentration in urine and serum6 and in tissues7 was determined by a modification of the molybdivanadate method for phosphate.In the statistical analyses, the t test* was used to determine the significance either of the mean differences or of the differences between group means. A P of <0.01 was considered significant.This experiment was conducted as follows. During a control period of three days the eight rabbits in the test group were fed a balanced stock diet of compressed pellets, containing 172 mEq of magnesium per kilogram. Base-line data for body weight. serum magnesium concentration, and urinary excretion of 144

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