Excretion Of Sr Research Articles

A simple assessment of the effect of strontium on the urinary excretion of calcium in Sprague Dawley rats.

This study was aimed at investigating the impact of varying concentrations of strontium (Sr) on calcium (Ca) excretion via the urine and determine its impact on kidney stone formation. Twenty adult male Sprague Dawley rats weighing between 200 and 300g were selected. The rats were randomly divided into four groups of five. One group was used as a control group while the other three groups were experimental. The diet of the rats was modulated over a 12week period to investigate the impact of Sr on the urinary excretion of Ca. Urinary samples were collected every 2weeks from the rats. The rats were fed water ad libitum. After the study the rats were euthanised and their kidneys harvested. Urine and kidney samples from the rats were analysed using Total Reflection X-Ray Fluorescence (TXRF). In the urine excretion of Ca increased with increased intake of Sr in the diet. Sr excretion via the urine also increased with increased dietary intake. There was a correlation of 0.835 at the significance level of 0.01 between Ca and Sr in the urine. However, for the kidneys, the varying concentration of Sr did not impact the retention of Ca in the kidneys. There was increased retention of Sr in the kidneys with increased dietary intake. In this study an increase of Sr in the diet resulted in an increase in urinary excretion of Ca.

Alginate Enhances Excretion and Reduces Absorption of Strontium and Cesium in Rats

Alginate (ALA), which is an intercellular polysaccharide associated with brown algae, is used as a food additive, a health food and a medicine. Here, we first examined the adsorption of strontium (Sr) and cesium (Cs) by ALA in vitro, and then evaluated the effects of ALA on absorption and excretion of Sr and Cs in rats, in order to evaluate its potential usefulness for minimizing radiation damage from materials released after a nuclear accident. Both Sr and Cs were concentration-dependently adsorbed by sodium alginate (ALA-Na) in vitro. In rats given diet containing either ALA-Na or calcium alginate (ALA-Ca) for two weeks, the plasma concentration of Sr gradually decreased compared with the controls (normal diet); however, in the case of Cs, the plasma concentration was decreased only in the ALA-Ca group, but not the ALA-Na group. Moreover, we examined the effect of preadministration of diet containing either ALA-Na or ALA-Ca on absorption of Sr and Cs administered orally as the chloride salts to rats. Absorption of both Sr and Cs was reduced in the ALA-Ca group, while absorption of only Sr was reduced in the ALA-Na group. Safety assessments indicated that ALA-Ca is safer than ALA-Na. These results indicate that ALA-Ca reduces absorption and promotes excretion of both Sr and Cs, while ALA-Na does so only for Sr.

Intraspecific variation in calcium and strontium accumulation / depuration in an epigeic earthworm species

The accumulation and depuration of Ca and Sr were measured in populations of the earthworm Lumbricus rubellus, originating from calcareous and acidic soils, following laboratory exposure to a Sr-rich soil and a control soil. Populations from acidic soils accumulated more Sr than those from calcareous soils, when placed in a Sr-rich soil. After transferal from a Sr-rich soil to Sr-free soil, all populations depurated the majority of their body Sr (84 %-96 %) whilst maintaining their body Ca concentration; the Sr excretion was greater in the populations originating from acidic soils. ICP-MS cation analysis demonstrated the majority of Ca and Sr to be located in anterior alimentary canal and the majority of Sr was lost from this region.

Calcium and Strontium Metabolic Studies in Patients on Capd

Strontium is known to affect calcium metabolism both experimentally and in clinical studies on conditions other than end-stage renal failure (ESRF) and continuous ambulatory peritoneal dialysis (CAPD). To investigate Sr metabolism in relation to that of Ca in ESRF patients undergoing CAPD, and the possible influence of the duration of treatment. Cross-sectional observational study. University medical center and Institute of Nuclear Physics. Twenty-four patients on CAPD; 14 chronic renal failure (CRF) patients not on dialysis, and 52 healthy controls. Calcium and Sr content of serum, urine or dialysate effluent, and selected dietary products. Calcium and Sr are absorbed by the intestinal tract of healthy subjects with equal efficiency. Serum Ca levels were considerably lower in CRF patients than in healthy subjects and patients on CAPD (p < 0.001). Serum Sr was significantly higher in both CAPD and CRF patients than in healthy controls (p < 0.001). The Sr/Ca ratio in the sera of the healthy subjects was defined by the preferential excretion of Sr over Ca by the kidney. This preferential excretion was lost during renal failure. During treatment there was a tendency for the uptake of both Ca and Sr to increase. Strontium is accumulated in the body during renal failure and CAPD cannot restore normal levels. Considering the varying effects of different doses of Sr on bone metabolism experimentally, it would be interesting to determine by further studies the possible significance of the observed Sr accumulation for renal bone disease.

Measurement of bone resorption by strontium excretion in prelabelled rats.

The body handles strontium (Sr) in a similar way to calcium (Ca) in that Sr is absorbed by the gut, concentrated in bone and excreted in urine and feces. In this study, rats were labelled with Sr during growth and later subjected to various treatments affecting bone resorption and Sr excretion was measured during and after treatment. Six weeks old Wistar rats were repeatedly s.c. injected with SrCl2. After a period of 2 weeks after the last Sr injection the rats were subjected to various treatments. Sr clearance was then measured weekly for 2 weeks. In the first experiment, the Sr labelled rats were sham-operated (sham) or ovariectomized (ovx) and urine collected afterwards. Sham rats were either treated with 4 daily s.c. clodronat injections at the beginning of the urine sampling, fed a low Ca diet (0.08% Ca) during the second sampling week or injected with saline. Urinary Sr excretion was decreased in the clodronate group during the first sampling week and increased in the Ca depleted group during feeding the low Ca diet. Sr excretion by ovx rats was similar to the sham control. In the second experiment, the effect of high-dose treatment with 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) or clodronate on bone resorption induced by Ca depletion was assessed by Sr output in urine and feces. Sr labelled rats were fed a low Ca diet and daily injected with 24,25(OH)2D3 or clodronate for 14 consecutive days. Clodronate significantly decreased Sr output during both sampling weeks. Treatment with 24,25(OH)2D3 resulted in an increased Sr output indicating an increase in bone resorption.

Bone resorption measurement with unusual bone markers: critical evaluation of the method in phosphorus-deficient and calcium-deficient growing rats.

An in vivo method to evaluate bone resorption in rats, by using unusual bone seekers not dependent on renal tubular transfer, is described and a critical evaluation of the method is made. In our experimental conditions, 85Sr and 177Lu are virtually exclusively localized in bone whereas 237Np remains unchanged in different soft organs, so that the concomitant use of these markers can be used for measuring bone resorption. If osteolysis occurs 21 days after the injection of these markers, under our experimental conditions, any increase in the urinary excretion of 177Lu and 237Np represents a rise in bone resorption, whereas an increase in Sr excretion reflects both and renal tubular events. According to our bone localization studies, the enhancement of Lu and Np excretion reflects primarily an increase in cortical bone resorption localized at the endosteal (Lu) and at the periosteal (Np) surfaces respectively. In addition, strontium is considered to be the marker of mineral resorption whereas Lu and Np, under our experimental conditions, would reflect the organic bone resorption. This method is tested in phosphorus-deficient rats and in calcium-deficient rats which exhibit disturbances of calcium metabolism at both the bone and kidney levels. In agreement with previous investigations, the use of these bone markers to evaluate osteolysis shows: (a) after a 1-week phosphorus deficiency, a slight increase in cortical bone resorption with a simultaneous fall in calcium and strontium renal tubular reabsorption, and (b) after a 1-week calcium deficiency, a high rise in cortical bone resorption with a simultaneous increase in the renal tubular reabsorption of calcium and strontium.

Effect of magnesium on radiostrontium excretion in man

The effect of intravenously administered magnesium on radiostrontium excretion was studied under strictly controlled dietary conditions in man. The results were compared with those obtained with equimolar amounts of calcium in the same patients. A single tracer dose of Sr 85Cl 2 was given intravenously in the control, the magnesium and the calcium studies. Infusions of magnesium sulfate or of calcium gluconate were given on the day of the intravenous injection of Sr 85 and on the subsequent two days. Both magnesium and calcium increased the urinary excretion of Sr 85, but calcium was more effective than magnesium in most cases. The difference in effect appeared to be due to differences in urinary calcium excretion induced by intravenous calcium and magnesium, the infusions of calcium resulting in higher excretion of urinary calcium than the infusions of magnesium. There was no effect of either intravenous magnesium or intravenous calcium on fecal Sr 85 excretion.

The Efficiency of Tetracycline in Removing Radiostrontium from Rats

Tetracycline did not increase the rate of excretion of Sr 85 in rats. Data are presented from a study on rats given an intraperitoneal injection of tetracycline, either as a single dose of 30 mg or a multiple dose of 150 mg, after the administration of Sr85Cl.

Comparison of intravenous infusion of stable strontium with the calcium tolerance test.

Data obtained by the calcium tolerance test (Ca TT) were compared with those obtained with the intravenous administration of an equivalent amount of stable Sr in 9 human subjects. Urinary Ca excretion increased in all subjects on the day of Sr (977 mg) infusion. The sum of the increase plus the amount of Sr excreted equaled the amount of the excess urinary Ca observed on the day of the Ca TT. In all subjects the percentage of Sr excreted was always less than that for Ca. On the days following the infusion, the elimination of Sr decreased exponentially from the 24th or 48th hr. After 7 days, the total quantity of Sr eliminated was between 6 and 43% of the administered dose. Plasma Sr levels rose gradually, reaching at the end of the infusion a peak of 10% of the infused dose per total plasma volume and declined thereafter with time. Plasma levels of Ca also increased, reaching a peak at the second hr and returning to the control values in 6 to 8 hr. From these results, it appears that the sum of the increased calciuria and of the Sr excretion, similarly to the excess calciuria following the Camore » TT, are an indication of the skeletal capacity to retain Ca. Moreover, the ratio of Sr excretion to the increase in calciuria on the day of Sr infusion was an index of the magnitude of the exchangeable pool. It appeared that Sr has the same effects as Ca on the parathyroid glands, and that its metabolism is controlled by the same homeostatic mechanism as that of Ca. (TCO)« less

Studies on the Relation between the Excretion of Sr and the Intake of Ca (Report 1)

This experiment was attempted to know how to prevent or reduce the effect of contamination by radioactive substances by fallout. There are many kind of radioactive substances in the fallout, and above all 90Sr and 137Cs seem to be most important.As it has been indicated that the behaviour of Sr in and out of our bodies is very close to that of Ca, the experiment on the relation between the Ca content of diet and the excretion of Sr was performed by using albino rats.Experimental: Adult albino rats weighing about 200g were subjected to this experiment, and they were divided into four groups, the Ist group was fed with a high Ca diet and the 2nd a low Ca diet during experimental period, and the 3rd was fed with these high and low Ca diets alternately for 6 days each during this experiment. 90Sr was injected into the abdominal cavity of the rat, 1.3μc per capita. The 4th group was fed by standard diet and 90Sr was injected together with relatively large amount of non-radioactive Sr.Results: The percentage of total excretion 90Sr during 24 days of the Ist, 2nd and 3rd groups were 15%, 8%, 14% respectively, and of the 4th group was about 25% during 18days. The amount of excretion of 90Sr of high Ca diet group was superior to that of the low Ca diet group, and that of the group non-active Sr injected was the highest of all.

Studies on the Relation between the Excretion of Sr and the Intake of Ca (Report 2)

In continuance to the previous report, the relation between Ca intake and 90Sr excretion was investigated with young albino rats.Experimental: 16 immature albino rats weighing about 70g were subjected to this experiment, and they were divided into two groups.The 1st group was fed with a high Ca diet (506mg%) and the 2nd group on a low Ca diet (86mg%). Radioisotope was administered by the single shot method i. e., only 90Sr was injected into the abdominal cavity of the rats, 1μc per capita.After the injection, urine and feces of the rats were collected every two days during the first 10days, thereafter both were collected occasionally. Ten days after the injection, a tip part of the tail of each rat was cut off for the estimation of retained amount of RI in bones, 60-65days after the injection the rats were killed and the one side hind leg, incisor were taken off for determination of deposit activity in hard tissue.Results: The amount of 90Sr excreted by the rats fed on the high Ca diet were higher than that of the low Ca fed group.The retained amount of 90Sr in hard tissue, especially, in the teeth was larger in the low Ca group than that of the high Ca group.

Studies on the Relation between the Excretion of Sr and the Intake of Ca (Report 3)

Studies on the Relation between the Excretion of Sr and the Intake of Ca (Report 3)