Quamme G A, Dirks J H
Ren Physiol. 1986;9(5):257-69. doi: 10.1159/000173090.
Present evidence suggests that the renal handling of magnesium is normally a filtration-reabsorption process as evidence for secretion is unsubstantiated. Magnesium reabsorption has distinctive features when compared with that of sodium and calcium. The proximal tubule concentration of magnesium rises to levels about 1.5 times greater than the glomerular filtrate and only 20-30% of the filtered magnesium is reabsorbed in this segment. Although the fractional reabsorption of magnesium is only half that of sodium, it changes in parallel with that of sodium in response to changes in extracellular fluid volume. The major portion of filtered magnesium (some 65%) is reabsorbed in the loop of Henle and evidence indicates that the thick ascending limb is the principal segment involved in magnesium absorption. Recent observations suggests that magnesium reabsorption in the ascending limb may be voltage dependent and secondary to active sodium chloride reabsorption. The loop of Henle appears to be the major nephron site where magnesium reabsorption is regulated possibly by cAMP-mediated hormones including parathyroid hormones, calcitonin, glucagon and antidiuretic hormone. About 10% of the filtered magnesium is delivered into the distal nephron. The distal tubule reabsorbs only a small fraction of the filtered magnesium which may be regulated by the same cAMP-mediated hormones involved in control of magnesium in the loop.
目前的证据表明，肾脏对镁的处理通常是一个滤过 - 重吸收过程，因为分泌的证据并不确凿。与钠和钙相比，镁的重吸收具有独特的特征。近端小管中镁的浓度升高至比肾小球滤过液高约1.5倍的水平，且在此段仅20 - 30%的滤过镁被重吸收。尽管镁的分数重吸收仅为钠的一半，但它会随着细胞外液量的变化与钠的重吸收平行变化。滤过镁的主要部分（约65%）在髓袢重吸收，证据表明厚壁升支是参与镁吸收的主要节段。最近的观察表明，升支中的镁重吸收可能依赖于电压，且继发于氯化钠的主动重吸收。髓袢似乎是肾单位中镁重吸收受调节的主要部位，可能受包括甲状旁腺激素、降钙素、胰高血糖素和抗利尿激素在内的cAMP介导的激素调节。约10%的滤过镁进入远端肾单位。远端小管仅重吸收一小部分滤过的镁，其可能受与髓袢中镁控制相关的相同cAMP介导的激素调节。
