Iron loading of cultured hepatocytes. Effect of iron on 5-aminolaevulinate synthase is independent of lipid peroxidation.
Iron loading of cultured hepatocytes. Effect of iron on 5-aminolaevulinate synthase is independent of lipid peroxidation.
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培养的肝细胞的铁负荷。
DOI：
10.1042/bj2120321
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Pomeroy,JS
中科院分区：
文献类型：
--
作者：
Shedlofsky,SI;Bonkowsky,HL;Sinclair,PR;Sinclair,JF;Bement,WJ;Pomeroy,JS
培养的鸡胚肝细胞用次氮基三乙酸铁负载铁。铁负载的定量细胞铁测定和超微结构研究证实。随着铁负荷，脂质过氧化，检测到的丙二醛释放到介质中，发生在12小时的线性速率，在此时间后，丙二醛的产生率下降。通过乳酸脱氢酶释放检测，未观察到细胞毒性。暴露于铁18小时后，在培养基中回收的丙二醛的量占总丙二醛的24-33%，所述总丙二醛可以通过将裂解的细胞与铁和抗坏血酸一起孵育产生。细胞谷胱甘肽不受铁刺激的脂质过氧化反应，但增加烯丙基异丙基乙酰胺。虽然铁负载本身对血红素合成的第一步和限速步骤5-氨基乙酰丙酸合酶的活性没有影响，但在致卟啉药物烯丙基异丙基乙酰胺存在下的铁负载使5-氨基乙酰丙酸合酶的水平增加了6倍，超过单独药物诱导的水平。抗氧化剂，丁基羟基甲苯，完全抑制铁刺激的脂质过氧化反应，但没有干扰铁负荷的影响，加强5-氨基乙酰丙酸合成酶的增加。暴露于铁18小时后，随后更换为新鲜培养基，细胞内剩余的铁在随后的18小时内没有刺激进一步的脂质过氧化，但在暴露于烯丙基异丙基乙酰胺时确实增强了5-氨基乙酰丙酸合酶的增加。因此，似乎脂质过氧化不是铁增强肝脏5-氨基乙酰丙酸合酶诱导的机制。
Cultured chick embryo hepatocytes were iron-loaded with ferric nitrilotriacetate. Iron-loading was confirmed by both quantitative cellular iron determinations and ultrastructural studies. With iron-loading, lipid peroxidation, as detected by malonaldehyde released into the medium, occurred at a linear rate for 12h, after which time the rate of malonaldehyde production decreased. No cell toxicity, as detected by lactate dehydrogenase release, was noted. The amount of malonaldehyde recovered in the medium after 18h of exposure to iron represented 24-33% of the total malonaldehyde that could be produced by incubating lysed cells with iron and ascorbate. Cellular glutathione was not affected by iron-stimulated lipid peroxidation, but was increased by allylisopropylacetamide. Although iron-loading by itself had no effect on activity of 5-aminolaevulinate synthase, the first and rate-limiting step in haem synthesis, iron-loading in the presence of the porphyrogenic drug allylisopropylacetamide increased levels of 5-aminolaevulinate synthase 6-fold over levels induced by the drug alone. The antioxidant, butylated hydroxytoluene, totally inhibited iron-stimulated lipid peroxidation, but did not interfere with the effect of iron-loading to potentiate an increase in 5-aminolaevulinate synthase. After 18h of exposure to iron, followed by a change to fresh medium, the iron remaining within the cells did not stimulate further lipid peroxidation over the following 18h, but did potentiate an increase in 5-aminolaevulinate synthase on exposure to allylisopropylacetamide. It therefore appears that lipid peroxidation is not the mechanism by which iron potentiates induction of hepatic 5-aminolaevulinate synthase.