Effect of arginine on tumor growth in rats.

Solutions (at pH 7.4) of i@-arginine monohydro chlorid& (50 mg/ml in Experiments A and B [Table 1] and 100 rng/ml in Experiments C to H [Tables 1 and 2]) were injected subcutaneously into half of the 805 rats, weighing 2OO—2@5O gm., of the Long-Evans strain bearing subcutaneous implants of either the U.C.L.A. fibrosarcoma or the Jensen sarcoma. An approximately 75-mm. cube of tumor tissue was implanted by trocar at one ventral site per animal in Experiments D to H, two such sites in Experiment C, and four sites in Experiments A and B. The administration of arginine was begun at the time of tumor implanta tion in Experiments A and B but was delayed until the tumor became palpable in all other ex periments. The control and experimental groups were matched as closely as possible in respect to the body weight of animals and size of tumors. The rats were maintained on Rockland pellets (Experiments A and B) or a modified Ershoff (12) diet (Experiments C to H). Body weight was de terinined periodically, and tumor size was esti mated from caliper measurements.