Dembo M, Sirotnak F M
Biochim Biophys Acta. 1976 Oct 19;448(3):505-16. doi: 10.1016/0005-2736(76)90303-5.
The kinetics of methotrexate transport in L1210 cells are described. Data derived from the measurmenets of initial influx, the complete time-course of uptake, intracellular steady-state level and unidirectional efflux were found to be consistent with a simple empirical equation containing three constants. Properties of the system include the following: (1) saturability of initial influx: (2) approach to steady state during uptake is exponential; (3) the half-time for drug uptake is independent of external concentration and equal to half-time for efflux; and (4) transport is concentrative at low external concentrations, whereas the reverse is true at high external concentrations. These observations are incorporated into a kinetic model which quantitatively accounts for the data on the basis of the hypothesis that influx and efflux take place via different carriers.
本文描述了甲氨蝶呤在L1210细胞中的转运动力学。通过对初始内流、摄取全过程、细胞内稳态水平和单向外流的测量所获得的数据，与一个包含三个常数的简单经验方程相符。该系统的特性如下：（1）初始内流的饱和性；（2）摄取过程中达到稳态的方式呈指数形式；（3）药物摄取的半衰期与外部浓度无关，且等于外流的半衰期；（4）在低外部浓度下转运是浓缩性的，而在高外部浓度下则相反。这些观察结果被纳入一个动力学模型，该模型基于内流和外流通过不同载体进行的假设，对数据进行了定量解释。
