Properties and regulation of a trans-plasma membrane redox system in rat liver.
Properties and regulation of a trans-plasma membrane redox system in rat liver.
复制标题
大鼠肝脏跨质膜氧化还原系统的特性和调节。
DOI：
10.1042/bj2040795
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
Crane,FL
中科院分区：
文献类型：
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作者：
Clark,MG;Partick,EJ;Crane,FL
1.研究了大鼠肝脏体外灌流对铁氰化物还原的调节作用。2.还原速率依赖于铁氰化物的供应速率，而与灌流液的氧气浓度无关。3.考察了pH的影响，在pH为7.4时还原速度最快，pH低于7.4时对还原速度的抑制作用大于高于7.4时的抑制程度。4.考察了底物对铁氰化物还原速率的影响。检测胞浆和线粒体NADH/NAD+对的还原剂。2-羟基丁酸酯(10 MM)、乳酸(10 MM)、甘油(10 MM)和乙醇(10 MM)各不起作用。二羟基丙酮(10 MM)对此有刺激作用。5.脱氢抗坏血酸(1 MM)刺激铁氰化物还原的速率；这种刺激似乎不是由于产生还原物质而排出的，以还原细胞外铁氰化物。6.考察了胰高血糖素和环磷酸腺苷对铁氰化物还原速率的影响。胰高血糖素对这一比率的抑制作用约为。30%和半峰抑制出现在0.1 nm处，对应于葡萄糖释放出现半峰刺激的浓度。环化AMP可促进葡萄糖释放，但对铁氰化物还原速率无明显影响。结论：肝脏还原细胞外铁氰化物的跨膜氧化还原系统受高血糖素的调节。底物二羟基丙酮也会改变这一速率。胰高血糖素的作用可能是直接的，因为它不能被环状AMP模仿，而且它是在接触激素后直接发生的。
1. Regulation of the reduction of ferricyanide by the isolated perfused rat liver was studied. 2. The rate of reduction was dependent on the rate of supply of ferricyanide and independent of perfusate oxygen concentration. 3. The effect of pH was also examined; the rate of reduction was optimal at pH 7.4 and was inhibited to a greater extent by pH values below 7.4 than those above 7.4. 4. The effects of substrates on the rate of ferricyanide reduction was assessed. Reductants of the cytosolic and mitochondrial NADH/NAD+couple were tested. 2-Hydroxybutyrate (10mm), lactate (10mm), glycerol (10mm) and ethanol (10mm) each had no effect. Dihydroxyacetone (10mm) stimulated the rate. 5. Dehydroascorbate (1mm), stimulated the rate of ferricyanide reduction; the stimulation did not appear to be attributable to the production of reduced substances that were excreted to reduce extracellular ferricyanide. 6. The effects of glucagon and cyclic AMP on the rate of ferricyanide reduction were examined. Glucagon inhibited the rate by approx. 30% and half-maximal inhibition occurred at 0.1 nm, corresponding to the concentration at which half-maximal stimulation of glucose release occurred. Cyclic AMP stimulated glucose release but had no significant effect on the rate of ferricyanide reduction. It is concluded that the trans-plasma membrane redox system of liver that reduces extracellular ferricyanide is regulated by glucagon. The rate is also altered by the substrate dihydroxyacetone. The effect of glucagon may be direct as it cannot be mimicked by cyclic AMP and it occurs directly following exposure to the hormone.