[Effect of methotrexate on oxygen consumption of L1210 cells and their isolated mitochondria]

Methotrexate, at doses inhibiting cell growth without any lethal effect, alters oxygen consumption in L 1210 cells as soon as 3 hrs. after culture. After a 24 hrs. treatment with methotrexate, there is a close relationship between cellular oxygen uptake and growth inhibition. These two effects are reversible. With mitochondria from treated cells, an inhibition of respiration is observed in the presence of glutamate-malate. No effect occurs with succinate. These results in vitro are compatible with concentrations used in patients.