Incorporation of C14-labeled carbohydrate into protein in the Walker 256 tumor

homogenates of tumor, liver, brain and kidney tissues excised from Walker 256 tumor animals were divided to 3 aliquots and incubated with C"-l, CU-2 and C"-3-lactate media respectively. C02 yields from each aliquot of experiment were compared to determine the oxidative pathway of intermedially metabolite of sugar and also incorpora• tion of C"•lactate into tissue protein. Results obtained were as follow. 1) Total C02 production rate of tumor tissue was averaged 10. 2±3. 2uM/hr/gm and those of control tissues were showed 27. 8±7. 2 in the liver, 44.0± 6.8 in the brain and 42.7±55 uM/hr/gm in the kidney tissue respectively. These data impressed general oxidative metabolism in the tumor tissues were inhibited compared with those of control tissues. 2) C02 yields from each carbon of lactate in the tumor and control tissues were compared. C02 yields from C-1 carbon of lactate were always larger than those from C-2 and C-3 carbon of lactates. in every tissues. However this difference in the tumor tissue is remarkable as compared with normal tissues. these data suggested that carboxyl carbon of lactate was easily oxidized into C02 in the tumor tissue as In the normal tissues but further oxidation of C•2 and C-3 carbon of lactate, which Is acetate unit, were remarkably inhibited in the tumor tissue. 3) Incorporation of radioactivities of each carbon of lactate into tissue protein was observed in order to trace the fate of 2 carbon compound which is inhibited further oxidation into C02 in the tumor tissue. Incorporations of radioactivities into protein in the CJI-I-Iactate incubation experiments were always lower than those in C"-2 and C"-3-lactate incubation experiments in tumor and control tissues but remarkable difference was observed in the tumor tissue as comparing with control tissue. Thus means remaining 2 carbon compound after decarboxylation of lactate were participate to protein synthesis relatively larger part in the tumor tissues than in the control tissues From the above data we suggested metabolic pathway of lactate in the tumor tissue as in the figure 1