DEOXYURIDINE SUPPRESSION TEST ON ISOLATED RAT BONE-MARROW CELLS AND THE IN-VITRO EFFECT OF BIDISOMIDE

The deoxyuridine suppression test was performed on isolated rat bone m arrow cells in order to study the effect of bidisomide, a new Class I antiarrhythmic agent, on folate-dependent DNA synthesis. Methotrexate and 5-fluorouracil, two known inhibitors of DNA synthesis, were includ ed in the study to validate the test system. Methotrexate and 5-fluoro uracil, at a concentration of 5.5 mu M, decreased thymidine incorporat ion into DNA by way of the de novo pathway (thymidylate synthase activ ity). The salvage pathway of DNA synthesis (thymidine kinase activity) , however, was not affected by these anticancer drugs. Bidisomide up t o 1 mM did not affect the folate-dependent thymidylate synthase activi ty, nor the thymidine kinase activity of isolated rat bone marrow cell s.