Effect of cross-reinnervation on the expression of GLUT-4 and GLUT-1 in slow and fast rat muscles.
We determined whether the twitch-velocity phenotype or the metabolic phenotype of a muscle influences the content of GLUT-4 and GLUT-1 proteins. The soleus (Sol) and extensor digitorum longus (EDL) muscles were cross-reinnervated (X-Sol, X-EDL). After 3 mo the X-EDL had become enriched in slow-twitch oxidative (SO) fibers (70.5% SO) compared with its control (3.8% SO), whereas the X-Sol became enriched in fast-twitch oxidative-glycolytic (FOG) fibers (78.6% FOG) compared with its control (10% FOG). Thus the twitch phenotype of X-Sol shifted to fast-twitch muscle, whereas X-EDL shifted to a slow-twitch muscle. In the X-EDL, the oxidative nature of the X-EDL was increased to 97% oxidative fibers compared with 43% oxidative fibers in the normal EDL. In the Sol the oxidative nature of the X-Sol was retained at 100%. GLUT-4 content was increased 1.6-fold in the X-EDL (P < 0.05) but was not changed in the X-Sol (P > 0.05). GLUT-1 content was increased fourfold in X-EDL but was not altered in the X-Sol. We conclude that GLUT-4 and GLUT-1 content in muscle is related to the oxidative phenotype of the muscle rather than the twitch-velocity phenotype.
Jóhannsson
E
E
Norwegian University of Sport and Physical Education, Oslo, Norway.
Waerhaug
O
O
Bonen
A
A
D000818:Animals; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000294:innervation*; D009417:Nerve Tissue / Q000637:transplantation; D010641:Phenotype; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D016042:Transplantation, Heterotopic
D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495679:Slc2a1 protein, rat; C495694:Slc2a4 protein, rat