caa a22 4500 388097477 CHVBK 20180307125307.0 cr unu---uuuuu 161130e199911 xx s 000 0 eng 10.1017/S0029665199001299 doi S0029665199001299 pii (NATIONALLICENCE)cambridge-10.1017/S0029665199001299 van Hall Gerrit The Copenhagen Muscle Research Centre, Rigshospitalet section 7652, 20 Tagensvej, DK-2200, Copenhagen N, Denmark Correction factors for 13C-labelled substrate oxidation at whole-body and muscle level [Elektronische Daten] [Gerrit van Hall] The oxidation of fatty acids, carbohydrates and amino acids can be measured by quantifying the rate of excretion of labelled CO2 following administration of 14C- or 13C-labelled substrates at whole-body and tissue level. However, there is a theoretical need to correct the oxidation rates for the proportion of labelled CO2 that is produced via oxidation but not excreted. Furthermore, depending on the substrate and position of the C label(s), there may also be a need to correct for labelled C from the metabolized substrate that does not appear as CO2, but rather becomes temporarily fixed in other metabolites. The bicarbonate correction factor is used to correct for the labelled CO2 not excreted. Recently, an acetate correction factor has been proposed for the simultaneous correction of CO2 not excreted and label fixed in other metabolites via isotopic exchange reactions, mainly in the tricarboxylic acid cycle. Changes in metabolic rate induced, for example, by feeding, hormonal changes and physical activity, as well as infusion time, have been shown to affect both correction factors. The present paper explains the theoretical and physiological basis of these correction factors and makes recommendations as to how these correction factors should be used in various physiological conditions. The Nutrition Society Bicarbonate nationallicence Acetate nationallicence Fatty acids nationallicence Carbohydrate nationallicence Exercise nationallicence Proceedings of the Nutrition Society Cambridge University Press 58/4(1999-11), 979-986 0029-6651 58:4<979 1999 58 PNS https://doi.org/10.1017/S0029665199001299 text/html Onlinezugriff via DOI 1 conference jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0029665199001299 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- van Hall Gerrit The Copenhagen Muscle Research Centre, Rigshospitalet section 7652, 20 Tagensvej, DK-2200, Copenhagen N, Denmark NATIONALLICENCE 773 0- Proceedings of the Nutrition Society Cambridge University Press 58/4(1999-11), 979-986 0029-6651 58:4<979 1999 58 PNS CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge