Rabbit hindlimb glucose uptake assessed with positron-emitting fluorodeoxyglucose

The feasibility of estimating skeletal muscle glucose uptake in vivo was examined by using the glucose analogue 2-[¹⁸F]deoxy-2-fluoro-D-glucose (2-[¹⁸F]FDG) in the rabbit hindlimb. A pair of collimated coincidence gamma photon detectors was used to monitor the accumulation of tracer in the tissue after 2-[¹⁸F]FDG injection. Time-activity curves were generated on a second-by-second basis under control conditions, during increased contractile activity, or hyperinsulinemia. The arterial input of 2-[¹⁸F]FDG, plasma glucose, lactate, free fatty acids, and insulin were determined. A graphical (Patlak plot) procedure was used to determine the fractional rate of tracer phosphorylation and therefore trapping in the muscle. From the graphical analysis, the estimated rate of glucose phosphorylation (R) in the unperturbed state was calculated to be 0.037 μmol · min^-1 · ml^-1 of tissue. During perturbation by electrical stimulation, an increase in the rate of tracer phosphorylation (K) was observed. No change in the rate of tracer phosphorylation was observed during hyperinsulinemia. The results support the use of 2-[¹⁸F]FDG and the graphical procedure for the noninvasive assessment of glucose uptake by skeletal muscle in vivo. The method described is sensitive to changes in the rate of tracer uptake with respect to time and physiological interventions.