Use of 3-Amino-l,2,4-triazole To Reduce Body Catalase Activity in Cancer Studies* ROBERT N . FEINSTEIN AND JULIA L. DAINKO

Heim, Appleman, and Pyfrom (1~) first showed that injection of the herbicide 3-amino-l,~,4triazole (AT) strikingly reduced the catalase activity of the liver, but not of the erythrocyte. This has since been amply confirmed (6, 13, 18), and it has been shown (6, 18) that AT per se is not an inhibitor of catalase but will, upon incubation in vitro, reduce the catalase activity of crude tissue preparations. The chief interest of AT, from the oncologists' point of view, is that it resembles the tumor toxohormone of Nakahara and Fukuoka (17) in its differential effect on the eatalase of the liver, but not of the erythrocyte. The present paper represents an at tempt to answer the following questions: (a) Why does AT affect the catalase of solid tissues but not of blood? (b) Is it possible to maintain a prolonged low level of total body catalase by the use of AT? (c) If such a low level is obtained and maintained, will a tumor implanted in such an animal be any more sensitive to fed hydrogen peroxide (14) or to irradiation, as recently suggested by Warburg (19, ~0)?