Kaya M, Küçük M, Kalayci R B, Cimen V, Gürses C, Elmas I, Arican N
Istanbul Faculty of Medicine, Department of Physiology, University of Istanbul, Capa, Turkey.
Can J Physiol Pharmacol. 2001 Sep;79(9):793-8.
Magnesium probably protects brain tissue against the effects of cerebral ischemia, brain injury and stroke through its actions as a calcium antagonist and inhibitor of excitatory amino acids. The effects of magnesium sulfate on cerebrovascular permeability to a dye, Evans blue, were studied during insulin-induced hypoglycemia with hypothermia in rats. Hypoglycemia was induced by an intramuscular injection of insulin. After giving insulin, each animal received MgSO4 (270 mg/kg) ip, followed by a 27 mg/kg dose every 20 min for 2.5 h. Plasma glucose and Mg2+ levels of animals were measured. Magnesium concentrations increased in the serum following MgSO4 administration (6.05+/-0.57 vs. 2.58+/-0.14 mg/dL in the Mg2+ group, and 7.14+/-0.42 vs. 2.78+/-0.06 mg/dL in the insulin + Mg2+ group, P < 0.01). Plasma glucose levels decreased following hypoglycemia (4+/-0.66 vs. 118+/-2.23 mg/dL in the insulin group, and 7+/-1.59 vs. 118+/-4.84 mg/dL in the insulin + Mg2+ group, P < 0.01). Blood-brain barrier permeability to Evans blue considerably increased in hypoglycemic rats (P < 0.01). In contrast, blood-brain barrier permeability to Evans blue was significantly reduced in treatment of hypoglycemic rats with MgSO4 (P < 0.01). These results indicate that Mg2+ greatly reduced the passage of exogenous vascular tracer bound to albumin into the brain during hypoglycemia with hypothermia. Mg2+ could have protective effects on blood-brain barrier permeability against insulin-induced hypoglycemia.
镁可能通过作为钙拮抗剂和兴奋性氨基酸抑制剂的作用，保护脑组织免受脑缺血、脑损伤和中风的影响。在大鼠胰岛素诱导的低温低血糖期间，研究了硫酸镁对脑血管对伊文思蓝染料通透性的影响。通过肌肉注射胰岛素诱导低血糖。给予胰岛素后，每只动物腹腔注射硫酸镁（270mg/kg），随后每20分钟给予27mg/kg剂量，持续2.5小时。测量动物的血糖和镁离子水平。给予硫酸镁后血清镁浓度升高（镁离子组为6.05±0.57 vs. 2.58±0.14mg/dL，胰岛素+镁离子组为7.14±0.42 vs. 2.78±0.06mg/dL，P<0.01）。低血糖后血浆葡萄糖水平降低（胰岛素组为4±0.66 vs. 118±2.23mg/dL，胰岛素+镁离子组为7±1.59 vs. 118±4.84mg/dL，P<0.01）。低血糖大鼠血脑屏障对伊文思蓝的通透性显著增加（P<0.01）。相反，用硫酸镁治疗低血糖大鼠后，血脑屏障对伊文思蓝的通透性显著降低（P<0.01）。这些结果表明，在低温低血糖期间，镁离子大大减少了与白蛋白结合的外源性血管示踪剂进入大脑的量。镁离子可能对血脑屏障通透性具有保护作用，防止胰岛素诱导的低血糖。
