Study 3. Plasma FFA clearance rate (K fa) and appearance rate (R fa) were calculated from plasma 14C-P kinetics according to previously described methods [20]. Indices of utilization rates of plasma substrate by tissues (R), specifically R g′, R gly, R f*, and R fs were calculated based on 14C-2DG, 13C-glucose, 3H-R-BrP, and 14C-P, respectively from the general relation: (2)R=C×m∗∫0Tc∗(t)dt, where C is the plasma substrate concentration (glucose or FFA), t is time, T is the time of tissue collection, m* is the tissue accumulation of tracer product at t = T, and c*(t) is the plasma tracer concentration.
