Regulation of cyclic AMP level and lactic acid production in Ehrlich ascites tumor cells

Abstract

1. 1.Quercetin (3,3′,4′,7-pentahydroxy flavone) at the concentration of 10 −4M, as well as 2·10 −2 M theophylline and 1.5·10 −4 M prostaglandin E 2 caused maximal rise of cyclic AMP in Ehrlich ascites tumor cells. 2. 2. No additional increase of cyclic AMP level in these cells was found when both quercetin (10 −4 M) and theophylline (2·10 −2 M) were present in the incubation medium. while combination of quercetin (10 −4 M) and prostaglandin E 2 (1.5·10 −4 M) has a synergistic effect on the level of cyclic AMP. 3. 3. Degradation of cyclic AMP by homogenate pf Ehrlich ascites tumor cells was inhibited by both quercetin and theophylline. 4. 4. Quercetin, and to a smaller but significant extent theophylline, inhibited the lactic acid production in Ehrlich ascites tumor cells while prostaglandin E 2 did not change the glycolytic rate in these cells. No synergistic inhibitory effect on lactic acid production was found when combinations of quercetin and prostaglandin E 2, quercetin and theophylline or prostaglandin E 2 and theophylline were tested. 5. 5. Treatment of Ehrlich ascites tumor cells with dextran sulfate abolished the inhibitory effect of quercetin on lactic acid production, while the effect of the bioflavonoid on cyclic AMP levels was not altered.