PRIOR MUSCULAR-CONTRACTION ENHANCES DISPOSAL OF GLUCOSE ANALOG IN THELIVER AND MUSCLE

To noninvasively investigate in vivo glucose disposal in muscle and li ver after exercise, F-19 magnetic resonance spectroscopy (F-19-MRS) wa s applied using 3-fluoro-3-deoxy-D-glucose (3FDG) as a metabolic probe , After 30 minutes of muscle contraction of rabbit hindlimb by a l-Hz electrical stimulation, 3FDG 250 mg/kg was injected intravenously and F-19-MRS was performed on the postcontracted hindlimb or the liver. Ra bbits subjected to muscle contraction showed 1.5- and 1.7-fold higher peaks for 3FDG signal intensity in the liver and muscle than those not subjected to it. 3FDG was converted to 3-fluoro-3-deoxy-gluconic acid (3FGA) in the muscle and liver, and 3FDG oxidation was not affected b y muscle contraction. During intraportal 3FDG infusion for 120 minutes at a dose of 2 mg.kg(-1).min(-1) after termination of muscle contract ion, the postcontracted rabbits showed a continuous increase in the si gnal intensity of 3FDG and a 2.1-fold higher total signal intensity of 3FDG than those not subjected to muscle contraction. In conclusion,F- 19-MRS allows direct noninvasive observation of 3FDG disposal in rabbi t muscle and liver. The increased intensity of 3FDG in the liver after muscle contraction suggests that exercise enhances disposal of the gl ucose analog in the liver, as well as in muscle, and these effects per sist for at least 2 hours after exercise. Copyright (C) 1998 by W.B. S aunders Company.