Colorimetric estimation of succinic dehydrogenase activity by neotetrazolium chloride as a tumor sensitivity test to chemotherapeutic agents.

In the search for tumor sensitivity test to chemotherapeutic agents succinic dehydrogenase activity by neotetrazolium chloride was measured colorimetrically. The rate of formazan production was proportional to the amount of Ehrlich ascites tumor cells, accelerated by the addition of ascorbic acid, and inhibited by the addition of iodoacetic acid. The inhibitory rate of formazan production of tumor cells treated with chemotherapeutic agents was well correlated with the survival time of mice. Of the chemotherapeutic agents, mitomycin C was the most effective, either singly or in combination with other drugs. Considering the mechanisms of action of drug and of the host's defense, an in. vivo tumor system was studied as a screening test for the chemotherapeutic agents.