개의 CO2-HCO3 pool의 교체율에 관한 연구

Abstract

After single injection of Na HC"03 into the normal dog, respiratory CO, and plasma samples were collected at intervals of 5 or 10 minutes. Both samples were analyzed for specific activities of C"O, and SA-time curves were plotted on the semilogarhythmic paper. 0,1 the basis of SA-tim~ curve, CO, pool, CO, space and turnover rates of C02 pool were calculated. In the calculation of CO, pool, errors dua to initial massive - 32- loss of radioactivities into respiratory CUOz before equilibriation of injected CUOz in the COz pool were corrected by shifting the t=O extrapolation to t=5 minutes and obtaing the total radioactivities in the body 5 minute after the single injection of NaHCu03 by substracting the redioactivities expired into respiratory COz during first 5 minutes from total radioactivities injected. Results obtained were as follow. 1. Comparisons were made between SA of respiratory CUOz and plasma CUOz• First 5 minutes samples were always higher about 60% in the respiratory CO2 than in the plasma COz and both samples collected 5 minute after single injection of CU02 were almost same in their SA of CUOz This fact means equilibriation of injected CUOz into COz pool of body were obtained at 5 minuter after the single injection. 2. SA-time curves of plasma COz can be divided into three exponential curve on the sirnilogarhythrnic paper. First component showed abrupt decline during 5 min, thereafter showed straight line until 60 min and showed another slower exponential curve after 60 min. This fact shows complex process of equilibriation of CUOz injected through at least 3 distribution compartments in which diffusion velocities of C02 were different each other. 3. CO2 pool were calculated by isotope dilution principle obtaining the SA of CUOz at t=O and t=5 minute by extrapolation on the SA-time curves. The former value uncorrected was 162mM and the other value corrected was 154.3 mM. There are about 5% difference between uncorrected and corrected values. accordingly CO2space showed 47.7% and 45.3% respectively. 4. Turnover rate of CO2 pool was calculated from slope of SA-time curve and obtained 65%/hr. Thus mean of 100.5 mM/hr of CO2 were turnovered in the CO2 pool. On the other hand. total CO2 production rate was showed mean of 93.6 mM/hr. Therefore, almost of COz furnovered from COz pool was expired into respiratory COz and about 7% of turnovered CO2 was incorporated into another substrates in the body.