Syapin P J, Tweari S, Noble E P
Adv Exp Med Biol. 1980;126:283-98. doi: 10.1007/978-1-4684-3632-7_23.
The effect of ethanol on an enzyme system within an intact functional plasma membrane has been studied using neural cells grown in culture. Rat C6 glioma cells in mono-layer culture were treated acutely or chronically with 100 mM ethanol and the effect of this exposure on the activity of ecto-5'-nucleotidase was determined. Acute exposure led to an increase in enzyme activity with maximum stimulation occurring at concentrations of 100 - 400 mM ethanol. Chronic treatment of cells with 100 mM ethanol for 4 - 8 days also caused an increase in ecto-5'-nucleotidase activity. Both the acute and chronic ethanol-induced stimulation of enzyme activity was completely reversible by removing the ethanol; the acute effects reversed immediately, whereas the chronic effects required several hours. The addition of Concanavalin A demonstrated that the effects on enzyme activity of both chronic and acute exposure to ethanol were blocked by modification of the external cell surface. The effect of chronic exposure to 100 mM ethanol was further localized to an action on the plasma membrane by studies which showed chronic exposure to have no effect on the intracellular 5'-nucleotidase activity. Furthermore, the occurrence of pharmacological tolerance to acute ethanol was observed in this plasma membrane system following chronic treatment of C6 cells with 100 mM ethanol. These findings are consistent with the hypothesis that mammalian neural cells can adapt to the chronic presence of ethanol through changes in their plasma membrane.
利用培养的神经细胞，研究了乙醇对完整功能性质膜内酶系统的影响。将单层培养的大鼠C6胶质瘤细胞用100 mM乙醇进行急性或慢性处理，并测定这种暴露对胞外5'-核苷酸酶活性的影响。急性暴露导致酶活性增加，在100 - 400 mM乙醇浓度下刺激作用达到最大。用100 mM乙醇对细胞进行4 - 8天的慢性处理也会导致胞外5'-核苷酸酶活性增加。急性和慢性乙醇诱导的酶活性刺激在去除乙醇后均可完全逆转；急性效应立即逆转，而慢性效应需要数小时。添加伴刀豆球蛋白A表明，慢性和急性暴露于乙醇对酶活性的影响均通过修饰细胞外表面而被阻断。通过研究表明慢性暴露对细胞内5'-核苷酸酶活性无影响，将慢性暴露于100 mM乙醇的作用进一步定位到质膜上。此外，在用100 mM乙醇对C6细胞进行慢性处理后，在该质膜系统中观察到对急性乙醇的药理学耐受性的出现。这些发现与哺乳动物神经细胞可通过质膜变化适应乙醇长期存在这一假说一致。
