VITAMIN FUNCTION IN LIVER STUDIED IN VITRO

将采用大鼠肝细胞培养物来研究 两种维生素对肝功能的影响 这些是维生素E和叶酸。 维生素E被认为是通过淬灭自由基而起作用的， 主要是由氧代谢产生的。 的存在 组织中过量的自由基被认为会导致 生理恶化，表现为衰老，冠心病， 结缔组织疾病和肿瘤发生。 我们将研究快速 维生素E，糖皮质激素可逆性膜功能障碍发生时， 肝细胞被放置在培养物中，以进一步了解 维生素E在这些过程中。 肝细胞膜的不稳定性 通过两个肝脏特异性转运系统的丧失来评估： 一种是转运去唾液酸糖蛋白， 系统参与细胞吸收溴磺酞，胆酸 酸和甲氨蝶呤。 调查旨在确定 这些运输系统损失的原因以及维生素E 稳定他们。 肝脏是叶酸的储存场所。 为了留住 叶酸必须通过组织转化为γ-谷氨酰衍生物。 肝细胞培养系统将用于研究合成和 这些衍生物的裂解和调节这些的因子 流程. 透性肝细胞和肝癌细胞已经被 开发用于原位研究γ-谷氨酰化反应。 的细胞 已经耗尽的叶酰聚谷氨酸辅酶将被用于 研究叶酸和叶酸拮抗剂的γ-谷氨酰化及其 调控 这些研究旨在了解哪些因素， 条件控制叶酸辅酶在肝脏中的储存和释放， 在癌症化疗中使用的抗叶酸剂可能对 这个过程 重点将放在谷氨酰化的改变 由胰岛素、糖皮质激素和胰高血糖素引起， 和叶酸含量。

Cultures of rat hepatic cells will be employed to investigate the role of two vitamins in liver function. These are vitamin E and folic acid. Vitamin E has been proposed to function by quenching free radicals which are generated primarily as a result of oxygen metabolism. The presence of excessive amounts of free radicals in tissues is believed to result in physiological deterioration which is manifested by aging, coronary disease, connective tissue disorders and tumorogenesis. We will examine the rapid vitamin E, glucocorticoid-reversible membrane dysfunction occurring when hepatocytes are placed in culture in order to further understand the role of vitamin E in these processes. The hepatocyte membrane instability will be evaluated by the loss of two liver specific transport systems: one which transports asialoglycoproteins and one which is an anion transport system which is involved in cellular uptake of bromosulfophthalein, cholic acid, and methotrexate. The investigations are designed to determine the reasons for the loss of these transport systems and way in which vitamin E stabilizes them. The liver functions as a storage site for folates. In order to be retained by tissues folates must be converted to Gamma-glutamyl derivatives. Hepatocyte culture systems will be used to investigate the synthesis and cleavage of these derivatives and the factors which regulate these processes. Permeabilized hepatocytes and hepatoma cells have been developed to study the Gamma-glutamylation reaction in situ. Cells which have been depleted of the folylpolyglutamate coenzymes will be employed to study the Gamma-glutamylation of folates and antifolates and its regulation. These studies will be designed to understand what factors and conditions control the storage and release of folate coenzymes in liver and what effects the antifolates utilized in cancer chemotherapy may have on this process. Emphasis will be placed upon alterations in glutamylation caused by insulin, glucocorticoids, and glucagon and also the growth state and folate content of the cells.