膳食缺镁对大鼠肾钙沉积的作用

Effect of dietary magnesium deficiency on nephrocalcinosis in rats

目的 :研究饲料中不同镁水平对大鼠钙、磷代谢的影响。评价低镁膳食在肾结石发生中的作用。方法 :SD大鼠 30只 ,随机分为 3组 ,单独喂养在全塑代谢笼中 ,饲以人工半合成饲料。组 1大鼠给予缺镁饲料 (镁86mg/kg) ,组 2饲料含适量镁 (5 4 8mg/kg) ,组 3为高镁饲料 (5 4 0 2mg/kg ,)。 2 5d适应性对喂饲养后 ,开始为期5d的代谢实验。结果 :尽管高镁组饲料镁含量比镁适量组高 10倍 ,但钙的表观吸收率仅下降了 2 .4 5 %。然而 ,高镁饲料却导致尿钙的排泄量增加了 3倍多 (从 4 2 7.8μg/d上升为 1378.6 μg/d) ,降低了钙的滞留。缺镁组大鼠肾脏重量显著升高 ,肾脏中钙、磷的沉积量增加 ,尤其是肾钙含量显著升高 [达 (2 .2 3± 2 .91)mg],约为镁适量组[(0 .0 5 2± 0 .0 0 6 )mg]的 4 3倍。结论 :低镁膳食很可能是肾结石形成的重要原因之一 ,而保证镁的充分摄入 。

Objective:To study the influence of different dietary magnesium on metabolism of calcium and phosphorus, evaluating effect of magnesium deficiency on nephrocalcinosis. Methods:30 Sprague Dawley male rats were divided into three groups, 10 each and fed in non-metal metabolic cages individually. The rats in the first group were fed Mg deficient diet (86 mg Mg /kg diet), in the second group were fed Mg adequate diet (548 mg Mg /kg diet), while in the third group fed Mg excess diet (5402 mg Mg /kg diet). After 25 days adaptation to pair-fed, a five-day metabolic experiment was carried on. Results:In spite of 10 times higher of magnesium levels in diets of group 3 than that of group 2, the apparent absorption of calcium in group 3 only decreased 2.45%. However, urinary Ca excretion was 3 times higher (1378.6μg/d) in group 3 compared with group 2 (427.8μg/d), so excessive dietary magnesium decreased retention of Ca. On the other hand, kidney weight in Mg deficient rats was significantly higher. Mg deficient diet promoted the deposits of Ca and P in kidney, especiallycalcium in kidney was high up to 2.23±2.91mg,43 times higher than that in Mg sufficient group(0.052±0.006 mg)Conclusions:Mg deficiency may be one of the important pathogenic factors in nephrocalcinosis. It may be an effective nutritional intervention for prevention of nephrocalcinosis to provide with sufficient magnesium in diet.