oxalates and Magnesium-Deficiency

Three types of hypercalciuria are described; their existence and frequent association with calcium urolithiasis in humans are accepted. Various dietary factors such as minerals, electrolytes, fluids, vitamin D, carbohydrates, proteins are discussed with regard to their ability to alter the nature and the degree of calcium excretion following their ingestion. It is emphasised that at present we have only limited knowledge on the chain of events linking calorie intake and the response of the kidney.

Topics: Adult; Aged; Animals; Calcium; Diet; Dietary Carbohydrates; Dietary Fats; Dietary Proteins; Female; Humans; Kidney; Magnesium Deficiency; Male; Middle Aged; Oxalates; Phosphates; Rats; Sodium; Urinary Calculi; Vitamin D

Topics: Animals; Calcium Phosphates; Humans; Magnesium Deficiency; Magnesium Oxide; Male; Oxalates; Pyridoxine; Urinary Calculi; Vitamin B 6 Deficiency

To clarify in vivo, using isolated small intestinal loops perfused with radioactive 14C-oxalate, whether intestinal hyperabsorption or reduced secretion is important in magnesium deficiency (MgD), as this is a potential cause of calcium oxalate urolithiasis.. Twenty-four Sprague-Dawley rats were either fed a standard diet (control, 12 rats) or a magnesium-deficient diet (MgD, 12 rats) for 19 weeks. One hour before the animals were killed, a defined length of a small intestinal loop was isolated and filled with 5 mL of 0.9% NaCl and a defined amount of intravenous 14C-oxalate applied. Using this method it was possible to determine the secretion of unlabelled oxalate into the intestinal lumen, from the specific activity in plasma.. Plasma oxalate levels doubled under MgD; urinary calcium and phosphorus also increased significantly, while urine oxalate tended to decrease. The secretion of oxalate into the intestinal lumen of MgD animals increased significantly, by five times that of the control. The relative supersaturation for calcium oxalate remained constant. Elementary analysis of renal tissue showed an increase in calcium and phosphorus under MgD, in the sense of nephrocalcinosis, but no concretions were detected (no nephrolithiasis).. In contrast to earlier studies, there is no evidence that hyperoxaluria is responsible for the possible development of urolithiasis in MgD. This was confirmed by calcium phosphate deposits in renal tissue, even though there was no evidence of oxalate urolithiasis. The increase in plasma oxalate seems to be completely compensated by strongly increased oxalate secretion into the intestinal lumen.

Topics: Animals; Calcium; Intestinal Absorption; Intestine, Small; Kidney; Magnesium; Magnesium Deficiency; Male; Oxalates; Phosphates; Rats; Rats, Sprague-Dawley

Spinach was evaluated for its bioavailability of magnesium in the experiment with magnesium-deficient rats. The effect of oxalic acid on absorption of dietary magnesium was also examined in the same experiment. After there were significant differences in the body weight of the rats between the control group and the magnesium-deficient group, and after the number of dead rats increased, the magnesium-deficient rats were divided into six groups. They were pair-fed for 8 days on the magnesium-deficient diet, magnesium-deficient diet supplemented with raw powdered spinach (R-sp), boiled powdered spinach (B-sp), or fried powdered spinach (F-sp), control diet supplemented with oxalic acid (Ox-C), and control diet (+Mg). On the 10th day, there was no significant difference in the food intake of the rats between the control group and magnesium-deficient group. However, the body weight, and body weight gain of the rats increased more significantly in the control group than in those of the magnesium-deficient group. Also, the contents of calcium and phosphorus in the liver and kidneys, and serum calcium content increased significantly in the magnesium-deficient rats compared with those of the control rats. However, the serum magnesium content decreased significantly in the magnesium-deficient rats. An especially large amount of calcium was accumulated in the kidneys of the magnesium-deficient rats. At the end of the experimental period, there were no significant differences in the food intake, body weight and body weight gain of the rats among the control group and each of the spinach-added groups. The body weight and body weight gain of the Ox-C rats decreased significantly in comparison with those of the control group and each of the spinach-added groups. Although, there were no significant differences in the concentrations of serum minerals (Mg, Ca and P) among each of the groups, kidney magnesium, calcium and phosphorus, and liver magnesium and phosphorus were significantly higher in each of the spinach added groups than those of the control, Ox-C and +Mg groups. A large amount of calcium was accumulated in the kidneys of the rats fed on the R-sp, B-sp, F-sp and Ox-C diets. However, the kidney calcium of each of the spinach-added groups markedly decreased in comparison with kidney calcium of the magnesium-deficient rats on the 10th day, when the magnesium-deficient rats were separated. There was no significant difference in the magnesium content of the left tib

Topics: Animals; Biological Availability; Calcium; Diet; Hot Temperature; Kidney; Liver; Magnesium; Magnesium Deficiency; Male; Minerals; Oxalates; Oxalic Acid; Phosphorus; Rats; Rats, Wistar; Spinacia oleracea

Calcium and oxalate uptake by renal brush border membrane vesicles (BBMV) was examined in magnesium-deficient and pair-fed control rats. Uptake studies were carried out by rapid filtration technique and rate of influx of calcium and oxalate as a function of extravesicular concentration (0.1 nM--1.0 mM) examined. Calcium uptake by renal BBMV exhibited saturable kinetics while oxalate uptake followed a biphasic transport mechanism showing saturable kinetics at low oxalate concentrations and passive diffusion at higher concentrations. In magnesium deficiency the kinetics of calcium and oxalate uptake by renal BBMV remained unaltered but the rate of uptake was significantly enhanced at all the extravesicular concentrations studied. Double reciprocal plot for calcium uptake showed no change in Vmax but a decrease in Km (2.08 mM) in magnesium--deficient rats as compared to pair-fed controls (Km = 5.00 mM). Similar plot for oxalate uptake showed an increase in Vmax (7.69 nmoles/8 min/mg protein) in magnesium deficient group as compared to pair-fed controls (5.55 nmoles/8 min/mg protein), while Km remained unchanged. The results of the present study indicate high risk of calcium oxalate stone formation in magnesium--deficient rats due to hyperabsorption and retention of calcium and oxalate by the renal tubular brush border membrane.

Topics: Animals; Calcium; Kidney Cortex; Kidney Tubules, Proximal; Magnesium Deficiency; Magnesium Sulfate; Male; Microvilli; Oxalates; Oxalic Acid; Rats; Rats, Wistar

Male weanling rats were maintained on magnesium-deficient diet for 30 d and compared with pair-fed control rats fed magnesium-supplemented diet. Magnesium deficiency led to slow growth and finally to a significant decrease in body weight (P < 0.001) accompanied by a significant hypomagnesaemia, hypomagnesuria and hyperoxaluria (P < 0.001 in each case) in experimental rats as compared to the control rats. Magnesium deficiency altered the glyoxylate metabolism in the liver and kidney mitochondria by significantly decreasing glyoxylate oxidation (by 26 per cent in liver and 17 per cent in kidney) and activity of alpha-ketoglutarate:glyoxylate carboligase enzyme (by 35 per cent in liver and 27 per cent in kidney) in the experimental animals. A significant increase in the specific activities of glycolic acid oxidase (P < 0.001) and glycolic acid dehydrogenase (P < 0.01) and a significant decrease in alanine transaminase (P < 0.01) was also observed in magnesium-deficient rats. No change in liver and kidney lactate dehydrogenase was observed. Thus magnesium deficiency in rats leads to accumulation of glyoxylate in the tissues, a part of which is converted into oxalate, thereby promoting hyperoxaluria.

Topics: Aldehyde-Ketone Transferases; Animals; Body Weight; Kidney; Liver; Magnesium Deficiency; Male; Mitochondria; Mitochondria, Liver; Organ Size; Oxalates; Oxidation-Reduction; Oxo-Acid-Lyases; Rats; Rats, Wistar

To examine the contribution of exogenous calcium and oxalate in magnesium deficiency, intestinal absorption of both calcium and oxalate was studied by preparing brush border membrane vesicles (BBMV). Purity of the BBMV was ascertained biochemically by enrichment of the marker enzyme alkaline phosphatase by 14-fold with a concomitant 90 per cent decrease in the basolateral marker enzyme Na+/K(+)-ATPase in the purified membrane preparation as compared to the respective homogenate in both the groups. Uptake studies were carried out by a rapid filtration technique. The kinetics were studied by measuring the rate of influx as a function of concentration (0.1-1.0 mM). BBMV from both the groups showed a linear positive relationship between the uptake rate and the concentration for both calcium and oxalate, thereby demonstrating that calcium and oxalate are transported through intestinal microvillus membrane by a simple passive diffusion process. However, the rate of uptake of calcium and oxalate was significantly higher in the magnesium-deficient group as compared to the pair-fed control group, as shown by the increase in the slope line for both calcium and oxalate (for calcium, control = 3.88, deficient = 5.86; for oxalate, control = 4.41, deficient = 7.20). Analysis of the lipid composition of the BBM revealed a significant decrease in the cholesterol content (P < 0.01) with a concomitant increase in the triglycerides (P < 0.01) and total fatty acid content (P < 0.001) in the magnesium-deficient group. Thus the results indicate that, although the mechanism of translocation of calcium and oxalate in the intestine is similar in the two groups, magnesium deficiency leads to hyperabsorption of both the ligands through alterations in the lipid composition of the membrane, thereby increasing the risk of stone formation.

Topics: Animals; Calcium; Cholesterol; Fatty Acids; Intestinal Absorption; Intestines; Kinetics; Magnesium Deficiency; Male; Microvilli; Oxalates; Oxalic Acid; Rats; Rats, Wistar; Sodium-Potassium-Exchanging ATPase; Triglycerides

The synergistic interaction of fructose and magnesium (Mg) deficiency on kidney calcification was compared in male and female rats. Male and female weanling rats were divided into four dietary groups: fructose or starch, with or without Mg. Rats were fed their respective diets for 9 weeks, and 24 h urine was collected to measure urinary output, pH, Mg, calcium (Ca), and oxalic acid. Rats were fasted overnight. After decapitation, blood was collected immediately, and kidneys were removed to determine their Mg and Ca content. Dietary fructose significantly increased kidney Ca in female rats fed deficient or adequate Mg diet and in male rats fed Mg-deficient diet only; the greatest kidney calcification occurred in female rats fed Mg-deficient diet (P less than 0.0001). Even in starch groups female rats fed the Mg-deficient diet showed some kidney Ca accumulation. The synergistic interaction of fructose and magnesium deficiency on nephrocalcinosis was significantly greater in female than in male rats. Low urinary output, optimal pH 6.8 for calcium phosphate precipitation, hypercalcaemia, hypercalciuria, hypomagnesuria, and low ratio of urinary Mg to Ca may independently or multifactorially contribute to nephrocalcinosis. The possible mechanism of this interaction is discussed.

Topics: Analysis of Variance; Animals; Calcium; Dietary Carbohydrates; Female; Fructose; Hydrogen-Ion Concentration; Kidney; Magnesium; Magnesium Deficiency; Male; Nephrocalcinosis; Oxalates; Oxalic Acid; Rats; Rats, Inbred Strains; Sex Factors; Starch

Previous studies have shown that magnesium deficiency accelerates renal tubular calcium oxalate monohydrate deposition in rats on chronic hyperoxaluric, lithogenic protocols. The present study was conducted to investigate the effect of magnesium deficiency on intratubular calcium oxalate formation in rats from the 1st day of administration of a hyperoxaluric agent. The objectives were to delineate early ultrastructural features of the formation, mechanisms of retention, and development of renal tubular crystal deposits and to characterize the crystalluria in rats on the hyperoxaluric/hypomagnesuric protocol. Intratubular calcium oxalate monohydrate deposits were found in magnesium deficient rats after only 24 hours of ad libitum administration of 1 per cent ethylene glycol drinking water. Animals on regular food diet did not display renal tubular deposition after 11 days of ethylene glycol administration. Strand- and sheet-like organic material emanating from the luminal wall of the tubules was adherent to the crystals, thereby serving to immobilize them within the tubule. Calcium oxalate monohydrate crystals predominated in the urines of hyperoxaluric/hypomagnesuric animals with intratubular deposits while dihydrate crystals were the primary constituent of urines from rats administered ethylene glycol alone (no intratubular deposition). The results support the supposition that under certain conditions magnesium deficiency is a significant risk factor for intrarenal calcium oxalate deposition and stone formation. Furthermore the identification of calcium oxalate monohydrate crystalluria may be an important indicator of the propensity toward intranephronic calcium oxalate formation and urolithiasis.

Topics: Animals; Calcium Oxalate; Crystallization; Ethylene Glycols; Kidney Calculi; Kidney Tubules; Magnesium Deficiency; Male; Microscopy, Electron, Scanning; Oxalates; Oxalic Acid; Rats; Rats, Inbred Strains

Topics: Crystallography; Ethylene Glycols; Hydroxyapatites; Kidney Calculi; Kidney Tubules; Magnesium; Magnesium Deficiency; Microscopy, Electron, Scanning; Oxalates

Seventy-seven patients with nephrocalcinosis as revealed by X-ray studies over a 10-year period are reviewed. A programmed clinical and metabolic study was performed on each case; the author's criteria included the different pathogenic factors considered in the etiologic definition of the disease. There were 22 cases with primary hyperparathyroidism, 19 with spongy kidney, nine with tubulointerstitial nephropathy, five with hyperoxaluria, five with distal renal tubular acidosis, four with esential hypomagnesemia, and three cases of miscellaneous etiology (vitamin D intoxication, Fanconi's syndrome, Bartter's disease). Ten other cases were classified as idiopathic nephrocalcinosis since no definite cause could be found. The clinical characteristics (symptoms, associated diseases, diet and medication intake, family history) and the biochemical findings are analysed for each group. The physiopathologic mechanisms, comparisons between each etiologic group, treatment, clinical course, and prognosis are commented on. The conclusion drawn is that nephrocalcinosis is a clinical syndrome of various etiologies which in most cases arises from an underlying metabolic disease.

Topics: Acidosis, Renal Tubular; Bartter Syndrome; Fanconi Syndrome; Humans; Hyperparathyroidism; Magnesium Deficiency; Medullary Sponge Kidney; Metabolic Diseases; Neoplasm Metastasis; Nephritis, Interstitial; Nephrocalcinosis; Oxalates; Radiography; Vitamin D

In a group of 57 children with urolithiasis hypomagnesaemia was found in 15 cases (26.3%). All children but one with abnormally low serum magnesium levels had recurrent or bilateral nephrolithiasis or nephrocalcinosis. Prevalence of hyperoxaluria and hypercalciuria, marked severity of the clinical features, abnormality of Ca metabolism and its responsiveness to MgO treatment were demonstrable in Mg deficiency.

Topics: Adolescent; Calcium; Child; Child, Preschool; Czechoslovakia; Humans; Infant; Kidney Calculi; Magnesium Deficiency; Oxalates; Recurrence

Topics: Animals; Calcium; Female; Growth Disorders; Hair; Kidney; Kidney Medulla; Liver; Magnesium; Magnesium Deficiency; Male; Oxalates; Phosphorus; Potassium; Rats; Skin Diseases; Sulfates; Vitamin B 6 Deficiency

Topics: Alanine; Animals; Anura; Dogs; Female; Foreign-Body Reaction; Glomerular Filtration Rate; Humans; Hypoparathyroidism; Magnesium Deficiency; Nutritional Physiological Phenomena; Oxalates; Rabbits; Rats; Solvents; Ultrasonic Therapy; Urinary Calculi

Topics: Calcium; Humans; Hungary; Kidney Calculi; Magnesium; Magnesium Deficiency; Oxalates; Phosphates; Water Supply

Topics: Animals; Calcium, Dietary; Cats; Humans; Magnesium Deficiency; Oxalates; Plants, Medicinal; Pyridoxine; Rats; Rheum; Urinary Calculi; Vitamin B 6 Deficiency

Topics: Alkalosis; Citrates; Humans; Magnesium Deficiency; Metabolism; Oxalates; Phosphates; Tetany

Topics: Aldehydes; Aminophenols; Apatites; Bone and Bones; Calcium; Calcium Carbonate; Calcium Phosphates; Calcium, Dietary; Coloring Agents; Glyoxal; Histocytochemistry; Kidney; Magnesium Deficiency; Oxalates; Rats; Research; Salts; Spine; Staining and Labeling; Uranium; Vitamin D