EFFECT OF AGE AND MAGNESIUM DEPLETION ON BONE MAGNESIUM POOLS IN RATS
EFFECT OF AGE AND MAGNESIUM DEPLETION ON BONE MAGNESIUM POOLS IN RATS
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DOI：
10.1172/jci107851
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发表时间：
1974-01-01
影响因子：
15.9
通讯作者：
TROW, R
中科院分区：
文献类型：
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作者：
ALFREY, AC;MILLER, NL;TROW, R
进行体内和体外研究来表征可交换骨镁库，并确定年龄和镁消耗对骨镁的影响。体外可洗脱骨镁的大小与体内可交换骨镁的大小之间存在高度显着的相关性（r=0.97）。为了表明可交换骨镁是表面限制的骨镁，在体内施用放射性镁后4小时进行洗脱研究。洗脱液中的比活性是死亡时血清中发现的比活性的85%，这表明可洗脱的和可交换的骨镁池基本上是相同的池。骨镁浓度随着年龄的增加而下降。骨镁的全部下降是表面限制分数减少的结果。由于骨晶体已被证明会随着年龄的增长而增大，从而导致表面积收缩，因此这将是对这一发现的最明显的解释。在镁耗尽期间，可交换池和不可交换池中的镁浓度均下降。可交换池中的分数变化远大于总或不可交换骨镁的变化，表明表面有限的镁池在镁耗尽期间是可用的。不可交换的骨镁库大小的变化似乎与镁消耗的持续时间比血清镁水平的变化更相关。该池中镁浓度的下降可能是在消耗期间持续形成低镁骨的结果。
In vivo and in vitro studies were carried out to characterize the exchangeable bone magnesium pool and determine what effect age and magnesium depletion has on bone magnesium. A highly significant correlation was found between the size of the in vitro elutable and in vivo exchangeable bone magnesium (r=0.97). To show that the exchangeable bone magnesium was the surface-limited bone magnesium, elution studies were performed 4 h after the in vivo administration of radiomagnesium. Specific activity in the eluant was 85% of that found in the serum at time of death, suggesting that the elutable and exchangeable bone magnesium pools were largely the same pool.Bone magnesium concentration fell with increasing age. The entire fall in bone magnesium was a result of a decrease in the surface-limited fraction. Since bone crystals have been shown to enlarge with aging with resulting contraction of the surface area, this would be the most apparent explanation for this finding. During magnesium depletion, magnesium concentration in both the exchangeable and nonexchangeable pools decreased. The fractional change in the exchangeable pool was much larger than the change in total or nonexchangeable bone magnesium, suggesting that the surface-limited magnesium pool is available during magnesium depletion. The change in size of the nonexchangeable bone magnesium pool appeared to be more related to the duration of magnesium depletion than the change in serum magnesium levels. The fall in magnesium concentration in this pool is probably a consequence of continuing formation of low magnesium bone during the depletion period.