Determination of organ substrate oxidation in vivo by measurement of 13CO2 concentration in blood

✍ Scribed by Gertie C. M. Beaufort-Krol; Janny Takens; Marieke C. Molenkamp; Gioia B. Smid; Willem G. Zijlstra; Jaap R. G. Kuipers

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 245 KB
• Volume: 33
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199804)33:4<328::aid-jms637>3.0.co;2-t

✦ Synopsis

Substrate oxidation by various organs in animals as well as in humans is usually studied by experiments in which radioactively labeled substrates are used and the production of is measured. In vivo, substrate oxidation by 14CO 2 an organ has, up to now, not been determined by means of stable isotopes. Problems in the determination of the concentration of in blood may have impeded the use of 13C-labeled substrates. For the determination of 13CO 2 concentration in blood a direct method for the determination of total concentration in blood was 13CO 2 CO 2 combined with the determination of the isotope ratio (13C/12C) of by isotope ratio mass spectrometry. The CO 2 intra-assay relative standard deviation of the concentration (mean : 19.26 mmol l-1 ; n = 7) was 0.8% . The CO 2 inter-assay relative standard deviation of the concentration in solutions of a weighed amount of CO 2 Na 2 CO 3 determined over a 5 year period was 0.64% (mean : 21.99 mmol l-1 ; n = 22). The intra-assay relative standard deviation of 13C in was 0.03% (mean 13C/12C : 0.0111557 ; n = 5). From the concentration in arterial CO 2 13CO 2 and venous blood, substrate oxidation by various organs can be calculated. As an illustration, the determination of myocardial glucose oxidation in lambs, both at rest and during exercise, is described.