Analysis of the transport mechanism for methotrexate in L1210 mouse leukemia cells

Studies on the transport mechanism for methotrexate in L1210 mouse leukemia cells are summarized. The results support the utilization of an obligatory anion exchange mechanism in which the uptake of methotrexate is coupled to the efflux of an intracellular anion. Gradients of anions could then serve as the energy source for the observed concentrative uptake of methotrexate. Intracellular anions which may participate in this exchange cycle are suggested to include phosphate and AMP.