[Studies on entero hepatic circulation of urea nitrogen in pregnant rat (author's transl)].

The purpose of this paper is to investigate the specific metabolism of the protein and amino acid during pregnancy from a standpoint of urea nitrogen recycling hydrolyzed by intestinal bacterial urease of pregnant rat. For this purpose, the activity of urease of the intestinal flora, and L-glutamate dehydrogenase (GDH) in liver mitochondria, the concentration of free ammonia and urea in the intestinal tract, portal vein and right ventricle of the rat were discussed. The results were: 1) The activity of urease moderately increased during pregnancy with the peak on 19th gestational day. 2) The concentration of free ammonia in the intestinal tract elevated slightly, and markedly elevated in portal vein, but seemed to be no specific change in right ventricle. The peak showed on 19th gestational day. 3) The activity of GDH increased markedly during pregnancy, and the protein synthesis was thought to be accelerated. 4) Urea concentration in intestinal tract and blood stream seemed somewhat increased. This results revealed that the urea recycling system and protein synthesis accelerated during pregnancy because of high urease and GDH activity. This phenomenon adapted the pregnant to nutrient of the fetus for growing and development, and introduced a new concept of maternal-fetal unit of nutrition, especially in protein metabolism.