Role of muscle in CO2 production after oral glucose administration in man

A significant increase in CO2 production, reflecting carbohydrate oxidation and/or fat synthesis, is observed in normal subjects after the ingestion of glucose. The anatomic site(s) of this CO2 production has not yet been localized, although liver and muscle are logical considerations. To assess the contribution of skeletal muscle to this process, we measured whole-body and forearm CO2 flux in normal, postabsorptive subjects after the ingestion of 100 g of glucose and calculated their total muscle CO2 production. In the basal state, muscle accounted for 19% of total CO2 production, and, after glucose administration, muscle CO2 production did not change significantly. Thus, muscle is not the principal site of the observed increase in CO2 production.