Marchionatti Ana M, Díaz de Barboza Gabriela E, Centeno Viviana A, Alisio Arturo E, Tolosa de Talamoni Nori G
Laboratorio de Metabolismo Fosfocálcico y Vitamina D "Dr. F. Cañas" Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, C.C. 35, Suc. 16, 5016, Córdoba, Argentina.
J Nutr Biochem. 2003 Aug;14(8):466-72. doi: 10.1016/s0955-2863(03)00078-0.
The effect of a single large dose of menadione on intestinal calcium absorption and associated variables was investigated in chicks fed a normal diet. The data show that 2.5 micro mol of menadione/kg of b.w. causes inhibition of calcium transfer from lumen-to-blood within 30 min. This effect seems to be related to oxidative stress provoked by menadione as judged by glutathione depletion and an increment in the total carbonyl group content produced at the same time. Two enzymes presumably involved in calcium transcellular movement, such as alkaline phosphatase, located in the brush border membrane, and Ca(2+)- pump ATPase, which sits in the basolateral membrane, were also inhibited. The enzyme inhibition could be due to alterations caused by the appearance of free hydroxyl groups, which are triggered by glutathione depletion. Addition of glutathione monoester to the duodenal loop caused reversion of the menadione effect on both intestinal calcium absorption and alkaline phosphatase activity. In conclusion, menadione shifts the balance of oxidative and reductive processes in the enterocyte towards oxidation causing deleterious effects on intestinal Ca(2+) absorption and associated variables, which could be prevented by administration of oral glutathione monoester.
在喂食正常饮食的雏鸡中研究了单次大剂量甲萘醌对肠道钙吸收及相关变量的影响。数据表明，每千克体重2.5微摩尔的甲萘醌会在30分钟内抑制钙从肠腔向血液的转运。从谷胱甘肽耗竭以及同时产生的总羰基含量增加来判断，这种作用似乎与甲萘醌引发的氧化应激有关。两种可能参与钙跨细胞转运的酶，如位于刷状缘膜的碱性磷酸酶和位于基底外侧膜的Ca(2+)-泵ATP酶，也受到了抑制。酶的抑制可能是由于谷胱甘肽耗竭引发的游离羟基出现所导致的改变。向十二指肠环中添加谷胱甘肽单酯可使甲萘醌对肠道钙吸收和碱性磷酸酶活性的作用逆转。总之，甲萘醌使肠细胞中氧化和还原过程的平衡向氧化方向转移，对肠道Ca(2+)吸收及相关变量产生有害影响，口服谷胱甘肽单酯可预防这种影响。
