Enhanced 5-F.U. mortality in rats eating definded formula diets

Rats eating nutritionally adequate defined-formula diets (D.F.D) before and following lethal i.p. injection of 5-fluorouracil exhibit increased mortality and shorter survival time than rats eating conventional Purina rat chow. Neither the presence of proteins in hydrolyzed form nor the nitrogen level in the D.F.D appear to be the crucial factor of enhanced lethality. The possible mechanisms and implications of the phenomenon are discussed.