Effects of starvation on guanidino compound metabolism in mice.

Arginine levels diminished markedly in the plasma during starvation, suggesting that plasma arginine level principally depends on food intake. Organ arginine levels were relatively stable except for an extraordinary increase in the pancreas at 96 h. Guanidinoacetic acid decreased dramatically in all organs within 24 h and low level were maintained thereafter, except for the brain (and plasma). Creatinine output increased after 24h of starvation. The increased creatinine output recovered to the control level after 48 h. A small but significant amount of guanidinosuccinic acid was detected in the normal liver and decreased transitorily after 24 h and increased after 48 h starvation, corresponded with an increased output in the 24 h urine excretion. Otherwise this decrease may be related to the transitory decrease in arginine level in the liver over the same time course. Methylguanidine in the muscle and gamma-guanidinobutyric acid in the liver decreased gradually during starvation. These results suggest that guanidino compounds levels in mouse organs are principally dependent on exogenous nitrogen.