18F-fluorodeoxyglucose and PET/CT for noninvasive study of exercise-induced glucose uptake in rat skeletal muscle and tendon.
OBJECTIVE
To investigate exercise-related glucose uptake in rat muscle and tendon using PET/CT and to study possible explanatory changes in gene expression for the glucose transporters (GLUT1 and GLUT4).


METHODS
The sciatic nerve in eight Wistar rats was subjected to electrostimulation to cause unilateral isometric contractions of the calf muscle. (18)F-Fluorodeoxyglucose was administered and a PET/CT scan of the hindlimbs was performed. SUVs were calculated in both Achilles tendons and the triceps surae muscles. To exclude a spill-over effect the tendons and muscles from an ex vivo group of eight rats were cut out and scanned separately (distance>or=1 cm).


RESULTS
Muscle contractions increased glucose uptake approximately sevenfold in muscles (p<0.001) and 36% in tendons (p<0.01). The ex vivo group confirmed the increase in glucose uptake in intact animals. GLUT1 and GLUT4 were expressed in both skeletal muscle and tendon, but no changes in mRNA levels could be detected.


CONCLUSIONS
PET/CT can be used for studying glucose uptake in rat muscle and tendon in relation to muscle contractions; however, the increased uptake of glucose was not explained by changes in gene expression of GLUT1 and GLUT4.
Skovgaard
Dorthe
D
Cluster for Molecular Imaging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. dskovgaard@dadlnet.dk
Kjaer
Michael
M
El-Ali
Henrik
H
Kjaer
Andreas
A
D000818:Animals; D019788:Fluorodeoxyglucose F18 / Q000494:pharmacology*; D005947:Glucose / Q000493:pharmacokinetics*; D051272:Glucose Transporter Type 1 / Q000096:biosynthesis; D051275:Glucose Transporter Type 4 / Q000096:biosynthesis; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D049268:Positron-Emission Tomography / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013710:Tendons / Q000000981:diagnostic imaging* / Q000378:metabolism*; D014057:Tomography, X-Ray Computed / Q000379:methods*
D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; C495679:Slc2a1 protein, rat; C495694:Slc2a4 protein, rat; D019788:Fluorodeoxyglucose F18; D005947:Glucose