Effect of various synthetic estrogens on the respiration of ascites tumor cells in vitro.

The effects of the synthetic estrogens diethylstilbesterol, hexosterol, dienesterol, and phloretin were compared with their capacity to inhibit the endogenous respiration of intact Ehrlich ascites, Adenocarcinoma 755 ascites, and Ehrlich-Lettr6 ascites cells. The Ehrlich ascites was found to be far more susceptible to respiratory inhibition than either the Adenocarcinoma 755 or the Ehrlich-Lettr6 ascites. Diethylstilbesterol and hexosterol were found far more effective inhibitors of endogenous respiration than dienesterol or phloretin. Substrate-induced respiration of lysed ascites cells was inhibited by the hormonal agents listed to approximately the same degree as that observed in whole cells. The addition of the synthetic estrogens dissolved in ethanol markedly increased the capacity of these agents to inhibit the respiration of intact tumor cells. The relative activity of these compounds and the relative susceptibility of the tumor types to these synthetic estrogens were unaltered by the presence of high levels of ethanol.