Hahn T J, Chase L R, Avioli L V
J Clin Invest. 1972 Apr;51(4):886-91. doi: 10.1172/JCI106883.
Hypocalcemia and resistance to exogenous parathyroid hormone have been reported in several clinical states associated with magnesium deficiency. On the basis of such observations, it has been suggested that magnesium depletion per se may result in impaired responsiveness of the adenyl cyclase-adenosine 3',5'-monophosphate (3',5'-AMP) system. To test this hypothesis, 4 wk old male parathyroidectomized rats were maintained on normal or magnesium-deficient diets for 4 wk and their responses to parathyroid hormone compared. Serum magnesium and calcium fell progressively in the magnesium-deficient group. Despite clinical and biochemical evidence of severe magnesium deficiency in these animals, renal production and excretion of 3',5'-AMP in response to parathyroid hormone was normal both in vitro and in vivo. Additionally, administration of either dibutyryl 3',5'-AMP or parathyroid extract to fasting magnesium-depleted rats produced a normal increase in serum calcium. Parathyroid hormone infusion studies demonstrated normal renal and skeletal responsiveness as measured by urinary excretion of calcium, magnesium, phosphate, and hydroxyproline. These data show that the effect of parathyroid hormone on 3',5'-AMP formation and excretion, the responsiveness of skeletal tissue to 3',5'-AMP, and the renal and skeletal system responses to parathyroid hormone are not altered by pure magnesium deficiency in the parathyroidectomized rat.
低钙血症和对外源性甲状旁腺激素的抵抗已在几种与镁缺乏相关的临床状态中被报道。基于这些观察结果，有人提出镁缺乏本身可能导致腺苷酸环化酶-腺苷3',5'-单磷酸（3',5'-AMP）系统的反应性受损。为了验证这一假设，将4周龄的雄性甲状旁腺切除大鼠分别用正常饮食或缺镁饮食喂养4周，并比较它们对甲状旁腺激素的反应。缺镁组的血清镁和钙逐渐下降。尽管这些动物有严重镁缺乏的临床和生化证据，但在体外和体内，它们对甲状旁腺激素反应时肾脏产生和排泄3',5'-AMP均正常。此外，给禁食的缺镁大鼠注射二丁酰3',5'-AMP或甲状旁腺提取物后，血清钙正常升高。甲状旁腺激素输注研究表明，通过钙、镁、磷酸盐和羟脯氨酸的尿排泄量测量，肾脏和骨骼的反应正常。这些数据表明，在甲状旁腺切除的大鼠中，单纯的镁缺乏不会改变甲状旁腺激素对3',5'-AMP形成和排泄的影响、骨骼组织对3',5'-AMP的反应性以及肾脏和骨骼系统对甲状旁腺激素的反应。
