The rate of valine incorporation into proteins with correction for valine recycling, measured in two brain tumor models and the cortex.
The tissue dilution factor (lambda) for the incorporation of valine into proteins in the rat cortex and in two different tumors, AA ascites and C6 glioma, was determined from measurements of specific activities in the tissue acid-soluble and aminoacyl-tRNA pools and in the plasma. A constant plasma specific activity was achieved by a constant infusion rate of [3H] valine. The data showed that the lambda for valine was the same in the cortex as in the tumors, and the recycling was approximately 36%. There was no difference in the lambda calculated on the basis of the specific activities in the tissue acid-soluble or aminoacyl-tRNA pools. The average dilution factor was found to be 0.64+/-0.05. The rate of valine incorporation into proteins was on average 3.2+/-0.4 and 4.9+/-0.4 nmol/g/min in the cortex for the groups of rats used in the AA ascites and C6 glioma experiments, respectively. In the AA ascites tumor the rate was approximately 41 and 29 nmol/g/min 4 and 7 days after tumor implantation, respectively, whereas in the C6 glioma the rate was approximately 41 and 72 nmol/g/min 6 and 13 days after inoculation, respectively. The tumors had, in comparison with the cortex, a significantly greater volume of distribution of valine. The amounts of valyl-tRNA were significantly greater in the tumors as compared with the normal cortex, with the exception of the glioma 6 days after implantation where the concentration was the same as in the cortex.
Jevric-Causevic
A
A
Cone Laboratory for Neurosurgical Research, McGill University, Montreal, Quebec, Canada.
Diksic
M
M
D000818:Animals; D001835:Body Weight; D002286:Carcinoma, Ehrlich Tumor / Q000473:pathology; D002540:Cerebral Cortex / Q000737:chemistry / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D005910:Glioma / Q000473:pathology; D007269:Injections, Intra-Arterial; D008433:Mathematics; D009368:Neoplasm Transplantation; D011506:Proteins / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014633:Valine / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology
D011506:Proteins; D012346:RNA, Transfer, Amino Acyl; D014633:Valine