ATP CONCENTRATION GRADIENTS IN CYTOSOL OF LIVER-CELLS DURING HYPOXIA
ATP CONCENTRATION GRADIENTS IN CYTOSOL OF LIVER-CELLS DURING HYPOXIA
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DOI：
10.1152/ajpcell.1985.249.5.c385
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发表时间：
1985-01-01
影响因子：
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通讯作者：
JONES, DP
中科院分区：
文献类型：
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作者：
AW, TY;JONES, DP
研究了两个ATP需要系统的活动与不同的亚细胞定位在细胞中的平均细胞ATP浓度变化。胞浆ATP-硫酸化酶活性与细胞ATP浓度呈线性关系，但质膜Na+-K+-ATP酶对ATP浓度的降低更为敏感。在细胞ATP浓度降低到对照的40%的条件下，Rb+摄取几乎为零。结果表明，位于肝细胞质膜中的ATP利用酶暴露于比线粒体周围的胞质液中存在的酶更低的ATP浓度。假设线粒体是球形的，ATP消耗在ATP浓度上为零级，对线粒体ATP径向扩散的分析表明，平均ATP供应半径随着线粒体ATP产生的减少而减小。因此，在有限的ATP供应期间，与线粒体平均距离较大的酶（例如，质膜ATP酶）比紧邻线粒体的酶（例如，细胞质酶）。因此，由于ATP产生和消耗系统的不均匀分布，ATP供应的微观异质性可以在没有膜区室化的细胞中发生。
The activities of two ATP-requiring systems with different subcellular localizations were studied in cells in which average cellular ATP concentration was varied. The cytosolic ATP-sulfurylase activity varied linearly with the cellular ATP concentration; however, the plasma membrane Na+-K+-ATPase was substantially more sensitive to decreased ATP concentration. Under conditions where the cellular ATP concentration was lowered to 40% of control, Rb+ uptake was nearly zero. The results indicate that ATP-utilizing enzymes located in the plasma membrane in liver cells are exposed to a lower ATP concentration than are enzymes present in the cytosolic fluid surrounding the mitochondria. Analysis of radial diffusion of ATP from mitochondria, assuming that mitochondria are spherical and ATP consumption is zero order in ATP concentration, shows that the average ATP supply radius decreases as mitochondrial ATP production decreases. Hence, during limited ATP supply, enzymes with a greater average distance from mitochondria (e.g., plasma membrane ATPases) experience a more dramatic decrease in ATP concentration than enzymes in close proximity to mitochondria (e.g., cytoplasmic enzymes). Thus microheterogeneity of ATP supply can occur in cells without membranal compartmentation due to nonuniform distribution of ATP-generating and ATP-consuming systems.