METHOTREXATE - STUDIES ON CELLULAR-METABOLISM .6. EFFECT ON CA-2+ TRANSPORT

The effect of the anti-cancer drug methotrexate (MTX), on liver mitoch ondria and digitonin permeabilized HeLa cells on Ca2+ uptake and relea se has been studied. Using arsenazo III as a Ca2+ indicator, MTX (0.4 to 1.6 mumol) caused a progressive decrease of Ca2+ liver mitochondria l influx and an increase in its efflux. Mitochondria of permeabilized HeLa cells exposed to MTX did not accumulate Ca2+ to the same extent a s observed in control preparations . MTX decreased the.uptake capacity of Ca2+, the rate of influx, and the maximum capacity of Ca2+ accumul ation in digitonin permeabilized HeLa cells. The possible mechanism of action of MTX is discussed.