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首页> 外文期刊>American Journal of Physiology >Description of glucose transport in isolated bovine mammary epithelial cells by a three-compartment model.
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Description of glucose transport in isolated bovine mammary epithelial cells by a three-compartment model.

机译：通过三室模型描述分离的牛乳腺上皮细胞中的葡萄糖转运。

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Initial rates of glucose entry into isolated bovine mammary epithelial cells display moderate degrees of asymmetry and cooperative interactions between export and import sites. The present study examined the hypothesis that these kinetic features are due to compartmentalization of intracellular glucose. Net uptake of 3-O-methyl-d-[1-(3)H]glucose (3-OMG) by isolated bovine mammary epithelial cells was measured at 37 degrees C. The time course of 3-OMG net uptake was better fitted by a double-exponential equation than by a single- or triple-exponential equation. Compartmental analysis of the time course curve suggested that translocated 3-OMG is distributed into two compartments with fractional volumes of 32.6 +/- 5.7% and 67.4 +/- 5.7%, respectively. The results support the view that glucose transport in bovine mammary epithelial cells is a multistep process consisting of two serial steps: fast, carrier-mediated, symmetric translocation of sugar across the cell plasma membrane into a small compartment and subsequent slow exchange of posttranslocated sugar between two intracellular compartments. A three-compartment model of this system successfully simulated the observed time course of 3-OMG net uptake and the observed dependence of unidirectional entry rates on intra- and extracellular 3-OMG concentrations. Simulations indicated that backflux of radiolabeled sugar from the small compartment to extracellular space during 15 s of incubation gives rise to the apparent asymmetry, trans-stimulation, and cooperativity of mammary glucose transport kinetics. The fixed-site carrier model overestimated the rate of glucose accumulation in cells, and its features can be accounted for by the compartmentalization of intracellular sugar.
机译：葡萄糖进入分离的牛乳腺上皮细胞的初始速率显示出中等程度的不对称以及进出口位点之间的协同相互作用。本研究检查了这些动力学特征是由于细胞内葡萄糖的区室化的假设。在37°C下测量了分离的牛乳腺上皮细胞对3-O-甲基-d- [1-（3）H]葡萄糖（3-OMG）的净摄取。更好地拟合了3-OMG净摄取的时间过程而不是单指数或三指数方程式。时程曲线的区间分析表明，易位的3-OMG分为两个部分，分别具有32.6 +/- 5.7％和67.4 +/- 5.7％的体积分数。结果支持以下观点：牛乳腺上皮细胞中的葡萄糖转运是一个多步骤过程，包括两个连续步骤：快速，载体介导的糖在细胞质膜上对称转移到小隔室中，以及随后缓慢转移后的糖之间的交换两个细胞内区室。该系统的三室模型成功地模拟了观察到的3-OMG净摄入量的时程以及观察到的单向进入速率对细胞内和细胞外3-OMG浓度的依赖性。模拟表明，在15 s的孵育过程中，放射性标记糖从小隔室向细胞外空间倒流，引起了乳腺葡萄糖转运动力学的明显不对称，反刺激和协同作用。固定位点载体模型高估了细胞中葡萄糖的积累速率，其特征可以通过细胞内糖的分隔来解释。

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