Does mitochondrial compartmentation of CO2 exist in man?
A comparison was made between the specific radioactivity of urea, and that of CO2 in breath, in urine and in arterialized blood, during a 36-h continuous infusion of 0.5 mCi and 100 mmol of sodium bicarbonate (NaH14CO3) into six normal male volunteers. After a period of equilibration, the mean specific radioactivity of urea was found to be only 16% below that of end expiratory CO2 and a similar amount below that of CO2 both in arterialized blood and in urine. This difference may be explained by isotopic dilution of 14CO2 by metabolic CO2 produced in the splanchnic tissues. It is concluded that, in these normal subjects, there is little or no compartmentation between cytosolic CO2 and the mitochondrial CO2 used for urea synthesis.
Fuller
N J
NJ
MRC Dunn Clinical Nutrition Centre, Cambridge, UK.
Elia
M
M
D000328:Adult; D001639:Bicarbonates / Q000008:administration & dosage / Q000378:metabolism; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002451:Cell Compartmentation; D006801:Humans; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D013997:Time Factors; D014508:Urea / Q000378:metabolism
D001639:Bicarbonates; D002250:Carbon Radioisotopes; D002245:Carbon Dioxide; D014508:Urea