Increased accumulation of methotrexate by murine tumor cells in vitro in the presence of probenecid which is mediated by a preferential inhibition of efflux.
Increased accumulation of methotrexate by murine tumor cells in vitro in the presence of probenecid which is mediated by a preferential inhibition of efflux.
复制标题
DOI：
--
复制
发表时间：
1981-03
期刊：
影响因子：
11.2
通讯作者：
F. Sirotnak;D. M. Moccio;C. Young
中科院分区：
文献类型：
--
作者：
F. Sirotnak;D. M. Moccio;C. Young
丙磺舒抑制L1210白血病细胞对[3 H]甲氨蝶呤的内流和外流。抑制内流所需的丙磺舒浓度明显大于抑制外流所需的丙磺舒浓度。测定的50%内流抑制的浓度为1.35 +/- 0.15（S.D.）该通量的抑制是竞争性的（Ki = 1.23 +/-0.2mM），并且在除去丙磺舒后被逆转。相比之下，测定的50%外排抑制浓度仅为0.12 +/- 0.016 mM，去除丙磺舒后抑制作用也逆转。由于丙磺舒对每个通量的抑制程度不同，稳态时细胞内[3 H]甲氨蝶呤的水平显著增加。在0.1和1 mM丙磺舒时，稳态水平分别增加2倍和2.6倍。这些观察到的增加与这些浓度下对每个通量的影响所预期的结果非常一致。从其他数据的抑制，在较高浓度的丙磺舒，最大的影响（3至4倍增加），在稳态水平将预期丙磺舒浓度为2和3 mM之间。一个类似的关系，抑制丙磺舒的流入和流出的[3 H]甲氨蝶呤也显示为肉瘤180和埃利希癌细胞。这些结果对于丙磺舒或相关有机离子在叶酸类似物治疗人类癌症期间的辅助使用具有药理学意义。
Carrier-mediated influx and efflux of [3H]methotrexate by L1210 leukemia cells was inhibited by probenecid. The concentration of probenecid required for inhibition of influx was markedly greater than that required to inhibit efflux. The concentration determined for 50% inhibition of influx was 1.35 +/- 0.15 (S.D.) mM. Inhibition of this flux was competitive (Ki = 1.23 +/- 0.2 mM) and was reversed after removal of probenecid. In contrast, the concentration determined for 50% inhibition of efflux was only 0.12 +/- 0.016 mM, and inhibition was also reversed after removal of probenecid. As a consequence of the different extent of inhibition of each flux by probenecid, the level of intracellular [3H]methotrexate at steady state was markedly increased. At 0.1 and 1 mM probenecid, the steady state level was increased 2- and 2.6-fold, respectively. These observed increases are in close agreement with that expected from the effect on each flux at these concentrations. From other data on the inhibition of each flux at higher concentrations of probenecid, a maximum effect (3- to 4-fold increase) in steady-state level would be expected at a probenecid concentration between 2 and 3 mM. A similar relationship between the inhibition by probenecid of influx and efflux of [3H]methotrexate was also shown for Sarcoma 180 and Ehrlich carcinoma cells. These results have pharmacological implications with respect to the adjuvant use of probenecid or related organic ions during folate analog therapy of human cancer.