| Abstract: | Treatment of L1210 cells with glucose, 1-methyl-3-isobutylxanthine, theophylline, and prostaglandins E1 and E2 was used to increase to varying degrees the endogenous level of cyclic adenosine 3':5'-monophosphate (cAMP). In an inverse manner these agents decreased the rate of methotrexate (MTX) transport into the cells. Azide, conversely, lowered the cAMP level and enhanced MTX transport. Quantitative information about this relationship was obtained by plotting the reciprocal rates of MTX transport as a function of cAMP levels. These data suggest that MTX transport is regulated by the level of cAMP. |
