Ryschon T W, Rosenstein D L, Rubinow D R, Niemela J E, Elin R J, Balaban R S
Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
J Lab Clin Med. 1996 Feb;127(2):207-13. doi: 10.1016/s0022-2143(96)90080-3.
The current laboratory approach to assessing magnesium status is based on determining the concentration of total Mg ((Mg)) in serum or plasma. This strategy is problematic in that the amount of Mg in blood is less than 1% of total body Mg and does not accurately reflect (Mg) in other tissues. Furthermore, the (Mg) of blood does not distinguish biologically active, ionized Mg from the bound fraction. The goal of this study was to determine intracellular ionized Mg ((Mg++)i) of skeletal muscle in vivo and to compare results with the (Mg) of blood constituents. (Mg++)i was determined in resting skeletal muscle by using phosphorus 31 magnetic resonance (31P-MR) spectroscopy. (Mg) was measured in serum (S(Mg)), serum ultrafiltrate (UF(Mg)), mononuclear blood cells (MBC(Mg)), and red blood cells (RBC(Mg)) by using atomic absorption spectroscopy or a colorimetric assay. In a sample of 60 healthy adult subjects, skeletal muscle (Mg++)i = 557 +/- 97 mumol/L (mean +/- SD); S(Mg) = 0.78 +/- 0.09 mmol/L; UF(Mg) = 0.60 +/- 0.12 mmol/L; MBC(Mg) = 13.8 +/- 2.3 mmol/L; and, RBC(Mg) = 1.92 +/- 0.33 mmol/L. A significant negative correlation was found between (Mg++)i and S(Mg) (r = -0.43, p < 0.05). S(Mg) was significantly lower (p < 0.05) and (Mg++)i significantly higher (p < 0.05) in women than in men, but neither was related to age. These findings provide new insight into the relationship between blood Mg measures and (Mg++)i of the largest soft tissue mass of the human body.
目前评估镁状态的实验室方法是基于测定血清或血浆中总镁（(Mg)）的浓度。这种策略存在问题，因为血液中的镁含量不到全身镁总量的1%，不能准确反映其他组织中的（Mg）。此外，血液中的（Mg）无法区分具有生物活性的离子化镁和结合部分。本研究的目的是测定体内骨骼肌细胞内离子化镁（(Mg++)i），并将结果与血液成分中的（Mg）进行比较。通过使用磷31磁共振（31P-MR）波谱法测定静息骨骼肌中的（Mg++)i。使用原子吸收光谱法或比色法测定血清（S(Mg)）、血清超滤液（UF(Mg)）、单核血细胞（MBC(Mg)）和红细胞（RBC(Mg)）中的（Mg）。在60名健康成年受试者的样本中，骨骼肌（Mg++)i = 557±97μmol/L（平均值±标准差）；S(Mg) = 0.78±0.09mmol/L；UF(Mg) = 0.60±0.12mmol/L；MBC(Mg) = 13.8±2.3mmol/L；RBC(Mg) = 1.92±0.33mmol/L。发现（Mg++)i与S(Mg)之间存在显著负相关（r = -0.43，p < 0.05）。女性的S(Mg)显著低于男性（p < 0.05），（Mg++)i显著高于男性（p < 0.05），但两者均与年龄无关。这些发现为血液镁测量值与人体最大软组织块的（Mg++)i之间的关系提供了新的见解。
