NITROGEN MOVEMENT BETWEEN HOST AND TUMOR IN MICE INOCULATED WITH EHRLICH ASCITIC TUMOR-CELLS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 44  (9) , 3831-3835
Abstract
Tumors function as a N trap and they compete with the host for N compounds. In experiments with whole animals infected with Ehrlich ascitic tumor cells, the Gln, Glu, Asn and Asp concentrations were determined for host plasma, ascitic liquid and tumor cells, throughout the period of tumor growth. Concentration gradients of Gln or Asn were created from the host tissues towards the ascitic liquid. The countergradient step from ascitic liquid to tumor cells may be overcome by an active transport process with an apparent Km for Gln of 3.1 .times. 10-4 M. A reverse flux of Glu and Asp was seen to take place from cells to plasma. In vitro incubations of tumor cells with near physiological concentrations of Gln, or Asn plus glucose, confirmed the host-to-tumor N movement previously deduced from the relative amino acid concentrations in plasma, ascitic liquid and tumor cells. The ammonemia detected in tumor-bearing mice at the terminal stage could result from the hydrolysis of Gln, which was rapidly metabolized by the tumor cells.