evolved was trapped in 0.5 ml of 2-phenethylamine and the radioactivity was r up
ID: 97384 • Letter: E
Question
evolved was trapped in 0.5 ml of 2-phenethylamine and the radioactivity was r up to 3 hours HCIO. The 1HC-CO, e Their pilot studies showed that HC-glucose utilization and HC-Co, release were linear up to oued A condensed version of data tables from the paper is given below: S.E. are given in umol/10 Table 1 Glucose concentration in all incubations was 4 mM. Mean values tS.E. ar cells/h from eight separate experiments "co McO, production from "CO, production production from from production from Lactate p | 37.2 ± 2.511 .61 Glucose consumption | production | tveHGle |fronm[3,ANGlel tve le Conditions Resting 123 5.10 ± 0.51 | 21.3±2.18 | 1.98 ±0.19 38.6 ±2.16 42.6 ± | | .61 11.6 ±1.01 20.1±2.15 | 0.93 20.1±2.15 0.93 ±0.06 11.6 ±1.01 36.1 ±324 11320 ±88 | The ratio (6-14C-labeled glucose to 'CO/3,4-4C-labeled the citric acid cycle is exclusively catalyzed by the pyruvate dehydrogenase reaction. / Thymocytes Proliferating 740 ± 509 estimate the acivity of tccle in relation to the glucose fux thoic senes to dehydrogenase. The calculation is based on the assumption that funneling of pyruvate into glucose to "CO glucose flux through pynuvate ) serves .. Table 2 Resting Thymocytes Proliferating Thymocytes cO, from 6-"c-glucose cO, from 3,4-"C-glucose 0.19 0.093Explanation / Answer
The metabolism of glucose and glutamine in freshly prepared resting and concanavalin A-stimulated rat thymocytes was studied. Concanavalin A addition enhanced uptake of both glucose and glutamine and led to an increase in oxidative degradation of both substrates to Co2. With variously labelled [14C] glucose, it was shown that the pathways of glucose dissimilation were equally stimulated by the mitogen. A disproportionately large percentage of the extra glucose taken up was converted into lactate, but concanavalin A also caused an increase in the oxidation of pyruvate as judged by the enhanced release of 14CO2 from [2-14C]-, [3,4-14C]- and [6- 14C]-glucose.
Addition of glutamine did not affect glucose metabolism. The major end products of glutamine metabolism by resting and mitogen-stimulated rat thymocytes were glutamate, aspartate, CO2 and NH3. Virtually no lactate was formed from glutamine. Concanavalin A enhanced the formation of all end products except glutamate, indicating that more glutamine was metabolized beyond the stage of glutamate in the mitogen-activated cells. Addition of glucose caused a significant decrease in the rates of glutamine utilization and conversion into aspartate and CO2 in the absence and in the presence of concanavalin A.
In the presence of glucose, almost all nitrogen of the metabolized glutamine was accounted for as NH3 released via the glutaminase and/or glutamate dehydrogenase reactions. In the absence of glucose, part (18%) of the glutamine nitrogen was metabolized by the resting and to a larger extent (38%) by the mitogen-stimulated thymocytes via a transaminase or amidotransferase reaction. Therefore this is the reason for total CO2 generated.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.