NITROGEN-METABOLISM DURING LIVER-REGENERATION

Nitrogen metabolism was investigated in regenerating liver-bearing rat s through the following parameters: (1) liver aminoacid content, (2) p lasma and urinary urea and creatinine, (3) plasma and urinary oxypurin es, uric acid and allantoin. Two groups of aminoacids were considered: (1) the essential aminoacids (phenylalanine, tyrosine, isoleucine, ly sine, leucine, valine, arginine, histidine and methionine); (2) the no n-essential aminoacids (aspartic acid, asparagine, glutamic acid, glut amine, alanine, glycine, serine, threonine and proline). Some of the f irst group tended to decrease, and those of the second group to increa se, immediately after partial hepatectomy. Few ketogenic aminoacids ar e probably oxidized to provide energy. The flux of aminoacids for gluc oneogenesis is minutely controlled, therefore, those of the second gro up being spared at first and set aside for protein synthesis, which in creases on the second and third days after partial hepatectomy. Plasma and urinary urea, oxypurines, uric acid and allantoin did not show an y significant variations after partial hepatectomy. The conclusion eme rging from the present research is that, although variations in aminoa cid composition and metabolism and in purine nucleotide metabolism hav e been demonstrated to occur in the regenerating liver, the overall ni trogen catabolism, as reflected by the principal end products, does no t undergo substantial variations. The remaining liver is able to fulfi l this function.