Magnesium Metabolism In Humans And Biological Systems

人体和生物系统中的镁代谢

• 批准号: 6675179
• 负责人: NADJA REHAK
• 金额: --
• 依托单位: CLINICAL CENTER
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6675179
• 关键词: blood tests; calcium; chelating agents; citrates; clinical research; disease /disorder prevention /control; hormone regulation /control mechanism; human subject; iatrogenic disease; magnesium; metal metabolism; metal metabolism disorder; parathyroid hormones; plateletpheresis

The secretion of parathyroid hormone (PTH) by the parathyroid gland is directly regulated by extracellular calcium ions (Ca2+) via the Ca2+-sensing receptor. However, there are reports of magnesium (Mg2+) effect on PTH secretion: acute hypermagnesemia can suppress PTH and it is suggested that the mechanism of suppression is similar to that of hypercalcemia. During platelet apheresis, the infused citrate forms complexes with both Ca2+ and Mg2+ ions and, therefore, decreases the concentration of the bioactive forms ("ionized" Ca and Mg) of both cations in the blood returned to the donor. The resulting hypocalcemia and concomitant hypomagnesemia could influence the PTH response and could be responsible for the citrate toxicity symptoms observed during apheresis. We investigated the time course of changes in the concentrations of PTH, citrate, ionized Mg (iMg) and ionized Ca (iCa), and other electrolytes, which occur during leukapheresis. Laboratory analyses of serum and urin specimens were performed during allogeneic peripheral blood progenitor cell donations (n=244) with and without prophylactic Ca. Marked increases in serum citrate concentration occured that were negatively correlated with a significant decreases in iCa and iMg (by up to 56 percent). The renal excretion of citrate was accompanied by significantly increased renal excretion of Ca and Mg. The serum concentration of both Ca and Mg remained decreased 24 hours after the procedure.Symptoms of citrate toxicity were more frequent in donors that had low serum total Mg concentration at the start of procedure. Prophylactic Ca infusions reduced the symptoms and attenuated the decreases in serum potassium.

甲状旁腺对甲状旁腺激素（PTH）的分泌直接通过CA2+传感受体直接受到细胞外钙离子（Ca2+）的调节。然而，有报道称镁（MG2+）对PTH分泌的影响：急性高镁血症可以抑制PTH，并建议抑制机理与高钙血症相似。在血小板的过程中，注入的柠檬酸盐与Ca2+和Mg2+离子均形成复合物，因此降低了血液中两种阳离子的生物活性形式（“电离” Ca和mg）的浓度，返回给供体。由此产生的低钙血症和伴随的低磁性血症可能会影响PTH反应，并可能导致柠檬酸盐毒性症状在（内部）期间观察到的毒性症状。我们研究了在白细胞术期间发生的PTH，柠檬酸盐，电离Mg（IMG）和电离CA（ICA）和其他电解质的时间变化的时间过程。在同种异体外周血祖细胞捐赠（n = 244）的情况下，进行了血清和尿液标本的实验室分析，有或没有预防性CA。与ICA和IMG的显着降低（高达56％）的显着相关的血清柠檬酸盐浓度显着增加。柠檬酸盐的肾脏排泄伴随着Ca和Mg的肾脏排泄显着增加。手术后24小时，CA和MG的血清浓度均降低。柠檬酸盐毒性的症状在手术开始时血清总MG浓度较低的供体中更常见。预防性CA输注减少了症状，并减轻了血清钾的降低。