Prevention by thymidine against toxicity and glucose uptake inhibition of methotrexate on cultured Ehrlich ascites tumour cells.

Methotrexate (MTX) arrested cell growth and inhibited 2-deoxy-D-glucose uptake of Ehrlich ascites tumour cells in vitro. The changes of glucose concentrations in the culture media did not affect the degree of suppression of cell growth by MTX. Thymidine (dThd) protected against the toxic effect of MTX on the cells. It also prevented the inhibition effect on glucose uptake of the cells by MTX. MTX significantly suppressed the maximal uptake rate of glucose (Vmax) while addition of dThd alleviated the suppression. The half-saturation constant of the uptake (Km) remained constant.