The method for introducing labeled glucose and detecting 14C-CO2 is as follows:
ID: 40624 • Letter: T
Question
The method for introducing labeled glucose and detecting 14C-CO2 is as follows: The cells and an O2/CO2 mixture (19:1) were shaken continuously and the uptake of radioactive glucose terminated by addition of 1M HClO4. The 14C-CO2 evolved was trapped in 0.5 mL of 2-phenethylamine and the radioactivity was counted. Their pilot studies showed that 14C-glucose utilization and 14C-CO2 release were linear up to 3 hours. A condensed version of data tables from the paper is given below: Table I: Glucose concentration in all incubations was 4 mM. Mean values +-S.E. are given in umo1/10^10 cells/h from eight separate experiments. Table II: The ratio (6-14C -labeled glucose to 14CO2/3,4-14C-labeled glucose to 14CO2) serves to estimate the activity of the citric acid cycle in relation to the glucose flux through pyruvate dehydrogenase. The calculation is based on the assumption that funneling of pyruvate into the citric acid cycle is exclusively catalyzed by the pyruvate dehydrogenase reaction.
Explanation / Answer
The comparison of the data seen in the first column shows the glucose consumption. In resting thymocytes we see a glucose consumption of 42.6 +/- 1.23 while in proliferating thymocytes, the consumption of glucose is high at 74 +/- 5.09.
This proves that proliferating thymocytes use more glucose. But when we compare the amount of lactate produced by the resting and the prolierative thymocytes, we can prove that proliferative thymocytes undergo altered glucose metabolism. For resting thymocytes 37.2 +/- 2.51 is the amount of lactate while in proliferative thymocytes, the number is 1320 +/- 88.6.
Even in the presence of oxygen, they behave like anaerobic cells to produce more lactate and less carbon dioxide. Since resting thymocytes produce less lactate and more carbon dioxide it proves that the experiment was carried out in the presence of oxygen.