Standley C A, Cotton D B
Department of Obstetrics and Gynecology, Wayne State University/Hutzel Hospital, Detroit, Michigan, USA.
Obstet Gynecol. 1996 Aug;88(2):184-8. doi: 10.1016/0029-7844(96)00144-5.
To examine the effect of changes in the state of magnesium balance on ionized magnesium and ionized calcium in serum and brain tissue of female rats.
Forty-two mature rats were used in the study. To induce hypermagnesemia, 12 rats received 270 mg/kg of magnesium sulfate intraperitoneally, followed every 20 minutes for 2 hours with 27 mg/kg magnesium sulfate. Ten control rats received an equal volume of saline. To induce hypomagnesemia, ten rats were placed on a magnesium-deficient diet for 4 (n = 5) or 8 (n = 5) days. Ten control rats were placed on basal diets of equal duration. Following treatment, rats were euthanized and serum and brain tissue were analyzed for ionized magnesium and calcium content.
Hypermagnesemia produced a significant increase in serum ionized magnesium (P < .05) and calcium (P < .05). In addition, brain levels of ionized magnesium were significantly increased (P < .05), whereas calcium levels significantly decreased (P < .05) particularly in the hippocampus, parietal cortex, and cerebellum. Hypomagnesemia induced by 4 days on a magnesium-deficient diet led to decreased serum ionized magnesium (P < .01) and total magnesium (P < .05) but did not affect brain magnesium levels. Brain levels remained unaltered even after 8 days of hypomagnesemia. Serum and brain ionized calcium were not affected during peripheral magnesium deficiency.
During peripheral magnesium deficiency, brain levels of ionized magnesium and ionized calcium are tightly regulated and appear unaffected. However, central levels of these electrolytes are altered under hypermagnesemic conditions. Thus, magnesium administration may change biologically active portions of magnesium and calcium in the brain.
研究镁平衡状态变化对雌性大鼠血清及脑组织中离子化镁和离子化钙的影响。
本研究使用了42只成年大鼠。为诱导高镁血症，12只大鼠腹腔注射270 mg/kg硫酸镁，随后每20分钟注射27 mg/kg硫酸镁，持续2小时。10只对照大鼠注射等量生理盐水。为诱导低镁血症，10只大鼠饲喂缺镁饮食4天（n = 5）或8天（n = 5）。10只对照大鼠饲喂相同持续时间的基础饮食。处理后，对大鼠实施安乐死，并分析血清和脑组织中的离子化镁和钙含量。
高镁血症使血清离子化镁（P < .05）和钙（P < .05）显著升高。此外，脑组织中离子化镁水平显著升高（P < .05），而钙水平显著降低（P < .05），尤其是在海马体、顶叶皮质和小脑中。缺镁饮食4天诱导的低镁血症导致血清离子化镁（P < .01）和总镁（P < .05）降低，但未影响脑镁水平。即使在低镁血症8天后，脑镁水平仍未改变。外周缺镁期间，血清和脑离子化钙未受影响。
在外周缺镁期间，脑组织中离子化镁和离子化钙水平受到严格调节，似乎未受影响。然而，在高镁血症条件下，这些电解质的中枢水平会发生改变。因此，镁的给药可能会改变脑中镁和钙的生物活性部分。
