Mahfouz M M, Zhou Q, Kummerow F A
Burnsides Research Laboratory, University of Illinois, Urbana, USA.
Magnes Res. 1994 Dec;7(3-4):207-22.
The cholesterol oxide (ChO) levels in the plasma and low density lipoproteins (LDL and VLDL) in four groups of rabbits fed for seven weeks either normal (NC) or high cholesterol (HC) with low or normal magnesium (Mg) diets were determined and compared with the NC group fed a standard rabbit diet. The plasma from the NC group contained low levels of different cholesterol oxides. These cholesterol oxides were significantly elevated in the plasma of rabbits fed a HC-normal magnesium or a HC-low magnesium diet. In the NC-low Mg group, 7 alpha-hydroxycholesterol, 7 beta-hydroxycholesterol and 7-ketocholesterol were elevated while the other cholesterol oxides remained within the normal range of the NC group. When the cholesterol oxides were assayed in the LDL and VLDL fractions as micrograms/mg protein, the fractions obtained from the groups fed NC-low Mg, HC-normal Mg or HC-low Mg diets showed higher levels of cholesterol oxides than the fractions obtained from the NC group. When LDL and VLDL fractions from the different groups were incubated at equal protein concentration with confluent endothelial cell monolayers, transendothelial albumin transfer was significantly increased by the lipoproteins from the experimental groups as compared to the control group. These results suggest that elevation of cholesterol oxides in magnesium deficiency or hypercholesterolaemia may be related to their atherogenic effects through decreasing the endothelial barrier function which could enhance the deposition of cholesterol rich lipoproteins into the arterial wall.
测定了四组兔子血浆及低密度脂蛋白（LDL和VLDL）中的胆固醇氧化物（ChO）水平。这四组兔子分别喂食正常（NC）或高胆固醇（HC）饲料，且镁（Mg）含量低或正常，为期7周，然后将结果与喂食标准兔粮的NC组进行比较。NC组血浆中不同胆固醇氧化物的含量较低。在喂食HC-正常镁或HC-低镁饮食的兔子血浆中，这些胆固醇氧化物显著升高。在NC-低Mg组中，7α-羟基胆固醇、7β-羟基胆固醇和7-酮胆固醇升高，而其他胆固醇氧化物仍在NC组的正常范围内。当以微克/毫克蛋白质为单位测定LDL和VLDL组分中的胆固醇氧化物时，来自NC-低Mg、HC-正常Mg或HC-低Mg饮食组的组分显示出比NC组更高的胆固醇氧化物水平。当不同组的LDL和VLDL组分在蛋白质浓度相等的情况下与汇合的内皮细胞单层一起孵育时，与对照组相比，实验组的脂蛋白显著增加了跨内皮白蛋白转运。这些结果表明，镁缺乏或高胆固醇血症时胆固醇氧化物的升高可能与其致动脉粥样硬化作用有关，其机制是通过降低内皮屏障功能，从而增强富含胆固醇的脂蛋白在动脉壁中的沉积。
