Abstract
When amino acid diet containing diammonium citrate alone in place of nonessential amino acid mixture (DAC diet) was singly supplemented with individual nonessential amino acids at the level cor-responding to that of control diet, the growth response, food intake, plasma free amino acid pattern and liver glutamate dehydrogenase activity were examined using Wistar strain male rats.
The proportion of essential and nonessential amino acids in the control diet was patterned according to the mixture shown to meet the requirements for young rats by Rama Rao et al., but each dietary level was restricted to 80% of their original one.
Single addition of glycine, glutamic acid or alanine to the DAC diet produced about the same weight gain as in the control group after 7 days' feeding in experiment 1, but could not prevent initial growth retardation consistently observed in rats fed ammonium salt containing diet. Throughout the similar 3 experiments single addition of glutamic acid or alanine seemed to somewhat improve the weight gain over that of the DAC group.
There was no difference in liver glutamate dehydrogenase activity between the control and DAC groups after 7 days' feeding.
Analyses of plasma free amino acid concentrations showed in general that the plasma alanine, glycine and serine levels were significantly lower in the DAC group than those in the control group. Even when glutamic acid, glycine, serine or alanine was added to the DAC diet, the plasma free serine, glycine and alanine concentrations were markedly reduced regardless of the same dietary level in both diets for a specific nonessential amino acid, except free alanine level in the rats fed glutamic acid. The concentration of the plasma free threonine was consistently lowered by the feeding of the DAC diet with or without added single nonessential amino acid. To the contrary, plasma free lysine level appeared to increase in all groups over the control group.
When the rats which had been on a 60% casein diet for 7 days were changed to the DAC diet, the initial growth retardation seemed to be lessened to some extent.
Nitrogen balance of the DAC group was significantly lowered on day 1 as compared with the control group, but rapidly restored near the control value in only 2 days.
