Characterization by flow cytometry of fluorescein-methotrexate transport in Chinese hamster ovary cells.
Characterization by flow cytometry of fluorescein-methotrexate transport in Chinese hamster ovary cells.
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DOI：
10.1002/cyto.990100109
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Y. Assaraf;L. Seamer;R. Schimke
中科院分区：
文献类型：
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作者：
Y. Assaraf;L. Seamer;R. Schimke
我们用流式细胞术研究了荧光素-甲氨蝶呤在中国仓鼠卵巢细胞中的转运。阿霉素-甲氨蝶呤似乎通过不同于甲氨蝶呤载体介导系统的机制进入细胞。这一结论得到以下观察结果的支持：1）白细胞介素-甲氨蝶呤同样良好地转运到向内甲氨蝶呤摄取缺陷的正常细胞和突变细胞中。2)叶酸及其还原态竞争性抑制甲氨蝶呤摄取，不改变荧光素-甲氨蝶呤转运。3)与甲氨蝶呤的流入（Q10 = 6-8）相比，阿霉素-甲氨蝶呤蓄积显示出较低的温度系数（Q10 = 1.6）。4)荧光素-甲氨蝶呤摄取的初始速率是浓度依赖性的，但不是饱和的。5)荧光素-甲氨蝶呤的摄取非常缓慢，8小时后达到稳态，而等摩尔浓度的甲氨蝶呤在20分钟后达到饱和。6）荧光素-甲氨蝶呤的初始流入速率不受甲氨蝶呤存在的影响。7)巯基反应性汞，它阻止甲氨蝶呤运输，不减少荧光素-甲氨蝶呤流入，而是刺激it. Thus，基于荧光素-甲氨蝶呤向内运输的不饱和性，其低的温度系数，和缺乏抑制与结构类似物，我们得出结论，荧光素-甲氨蝶呤积累在仓鼠细胞中的被动扩散过程。
We have studied by flow cytometry the transport of fluorescein-methotrexate in Chinese hamster ovary cells. Fluorescein-methotrexate appears to enter cells via a mechanism different from the carrier-mediated system for methotrexate. This conclusion is supported by the following observations: 1) Fluorescein-methotrexate is transported equally well into normal and mutant cells defective in the inward methotrexate uptake. 2) Folic acid and its reduced states, which competitively inhibit methotrexate uptake, do not alter fluorescein-methotrexate transport. 3) Fluorescein-methotrexate accumulation exhibits a low temperature coefficient (Q10 = 1.6) compared with the influx of methotrexate (Q10 = 6-8). 4) Initial rates of fluorescein-methotrexate uptake are concentration dependent but are not saturable. 5) Fluorescein-methotrexate uptake is very slow and reaches steady state after 8 h, whereas at an equimolar concentration methotrexate reaches saturation after 20 min. 6) Initial influx rates of fluorescein-methotrexate are not affected by the presence of methotrexate. 7) Sulfhydryl-reactive mercurials, which block methotrexate transport, do not reduce fluorescein-methotrexate influx, but rather stimulate it. Thus, based on the nonsaturability of fluorescein-methotrexate inward transport, its low temperature coefficient, and lack of inhibition with structural analogs, we conclude that fluorescein-methotrexate is accumulated in hamster cells by a passive diffusion process.