REGIONAL ACETATE KINETICS AND OXIDATION IN HUMAN VOLUNTEERS

We have used a 3-h primed continuous infusion of [1,2-C-13]acetate in five fasted (24 h) volunteers to quantify splanchnic and leg acetate m etabolism (protocol 1). Fractional extraction of acetate by both tissu es was high (similar to 70%), and simultaneous uptake and release of a cetate were observed. Labeled carbon recovery in CO2 was 37.9 +/- 2.3% at the whole body level, 37.7 +/- 1.5% across the splanchnic bed, and 37.3 +/- 2.9% across the leg. Furthermore, we calculated whole body l abeled carbon recovery during 15 h of [1,2-C-13]acetate infusion in th ree volunteers (protocol 2). Whole body acetate carbon recovery in CO2 was significantly higher (66.7 +/- 4.5%) after 15 h of tracer infusio n than after 3 h. We conclude that acetate is rapidly taken up by the leg and splanchnic tissues and that the percent recovery of CO2 from t he oxidation of acetate is heavily dependent on the length of acetate tracer infusion. In the postabsorptive state, labeled carbon recovery from acetate across the leg and the splanchnic region is similar to th e whole body CO2 recovery.