GROWTH-INHIBITION OF SUBCUTANEOUSLY TRANSPLANTED HEPATOMAS WITHOUT CACHEXIA BY ALTERATION OF THE DIETARY ARGININE-METHIONINE BALANCE

Previous studies have shown that alteration of the dietary arginine-me thionine balance by use of synthetic L-amino acids inhibits tumor grow th of a subcutaneously transplanted Morris hepatoma at the expense of maintaining body weight. However, L-methionine is susceptible to degra dation and, therefore, may contribute to a deficiency state. The prese nt studies were performed to determine whether growth of subcutaneous hepatoma transplants is inhibited, and body growth maintained, when ra ts are fed diets containing L-methionine in replacement of N-acetyl-L- methionine (NALM) for 28 days. Tumor-free and tumor-bearing rats fed a control diet, with amino acids replacing protein, had gains in body w eight: 31.3 +/- 1.0 and 19.1 +/- 0.5 g (12% and 7%), respectively. Rat s fed sh experimental diets, with varying L-arginine-NALM balances, ha d body weight gains ranging from 18.4 +/- 0.3 to 26.7 +/- 0.9 g (7-10% ). Tumor weight of control rats was 10.65 +/- 0.24% of body weight. Di ets supplemented with L-arginine in combination with normal and defici ent NALM decreased tumor weights by 35% and 38%, respectively. It is c oncluded that dietary replacement of L-methionine with NALM and supple mentation with L-arginine inhibits growth of a subcutaneously transpla nted Morris hepatoma in the absence of cachexia.