The effect of tryptophane on the urinary excretion of nicotinic acid in rats.

Krehl et al. (1,2) have observed a growth retardation in rats when large amounts of corn grits were included in a low protein ration. The addition of either Z(-)-tryptophane or nicotinic acid corrected the deficiency and allowed normal growth to proceed. The beneficial action of tryptophane has also been observed in nicotinic acid deficiency in the chick (3) and the mouse (4). Although recent results (5) indicate that corn is not an essential dietary component for the production of the deficiency state in the rat, a pellagragenic agent in corn has been reported for the mouse (6). In order to eludidate the interchangeable r&e of tryptophane and nicotinic acid, we have studied the effect of tryptophane and other substances on the urinary excretion of nicotinic acid derivatives in rats on corn and non-corn rations. The results of these experiments are reported here.