고온 및 한냉 환경이 흰쥐의 C14-포도당 대사에 미치는 영향

Abstract

The role of C14·glucose in energy metaboism of rats were studied in twenty six rats under warm and cold environment. Rats were kept in a constant temperature animal chamber of which temperature was maintained at 20°C in the first control group, the second group animals were kept at 4°C and the third warm acclimated group animals were kept at 33°C. In every run of experiment, hourly blood and respiratory C02 samples were collected after single injection of C14-glucose. Bloods gas samples were analyzed for blood sugar levels, total C02 production rates and their radioactivities. On the basis of specific activities(SA)-time curves of blood glucose and respiratory C02 in which both SA decreased exponentially with time, glucose pools, glucose spaces, relative specific activities, turnover rates of glucose pool and relative glucose disappearance(RGD) were calculated by isotope dilution method in each group. The following data were obtained. 1. Average blood sugar level was 75±11 mg % in the first group, 102±15mg % in the second group and 77±9. 0 mg % in the third group. The concentrations of liver glycogen averaged 5.3±1.2 mg/gm in the first group, 4.8±1.5 mg/gm in the second group and 7.3±2.3mg/gm in the third group, respectively. In the cold acclimated group, blood sugar level was elevated and concentration of liver glycogen was decreased compared with the control group. However, there were no remarkable differences in the blood sugar level and concentration of liver glycogen between control and warm acclimated group. 2. Average glucose pool size was 15.4±3.0 mg/lOO gm in the first group, 28.6±2.0 mg/lOO gm in the second group and 17.2±3.1mg/IOOgm in the third group. Glucose space in each group was 20.9±6.9 % in the first group and 28.0±5.0 % in second group and 22.4±3.1 % in the third group, respectively. Values in glucose pool and glucose space were remarkably increased in the cold acclimated group. However there were little differences between warm acclimated group compared with control group. 3. There were little differences in the turnover rates of glucose pools between each group, showing 95.8± 19.0 %/hr in the first group, 98.0±8.7%/hr in the second group and 81.6±9.8 %/hr in the third group, However, glucose consumption rate in the cold acclimated group increased remarkably because of their larger pool size of glucose. 4. The total CO2 production rate was a mean of 1.56±0.11 mM/hr/IOO gm in the first group, 1.96± O. 2mM/hr/100 gm in the second group and 1.30± 0.15 mM/hr/lOO gm in the third group. Relative specific activities(RSA) which represent the fraction of CO2 derived from glucose to total CO2 production rate averaged 13.I±3.0 % in the first group, 18.I± 1.2 % in the second group and 116±1.9 % in the third group. The CO2 delivery rate from glcose or oxidation of glucose in the cold acclimated group was remarkably increased because of increases in both values of total CO2 production rate and RSA. On the other hand, oxidation rate of glucose was decreased in the warm acclimated group. The relative glucose disappearances into CO2 (RGD) which are the fractions of glucose oxidized into respiratory CO2 to total glucose consumption rates were calculated mean of 41.5±11.7 % in the control, 37.8±6.5 % in the cold acclimated group and 32.8±4. 4 % in the warm acclimated group. From the data of RGD in each group, rates of glucose oxidation were proportionatly increased with glucose disappearance rates.