Glucose transporter protein content and glucose transport capacity in rat skeletal muscles.
The relationships among fiber type, glucose transporter (GLUT-4) protein content, and glucose transport activity stimulated maximally with insulin and/or contractile activity were studied by use of the rat epitrochlearis (15% type I-20% type II2a-65% type IIb), soleus (84-16-0%), extensor digitorum longus (EDL, 3-57-40%), and flexor digitorum brevis (FDB, 7-92-1%) muscles. Insulin-stimulated 2-deoxy-D-glucose (2-DG) uptake was greatest in the soleus, followed (in order) by the FDB, EDL, and epitrochlearis. On the other hand, contractile activity induced the greatest increase in 2-DG uptake in the FDB, followed by the EDL, soleus, and epitrochlearis. The effects of insulin and contractile activity on 2-DG uptake were additive in all the muscle preparations, with the relative rates being FDB greater than soleus greater than EDL greater than epitrochlearis. Quantitation of the GLUT-4 protein content with the antiserum R820 showed the following pattern: FDB greater than soleus greater than EDL greater than epitrochlearis. Linear regression analysis showed that whereas a relatively low and nonsignificant correlation existed between GLUT-4 protein content and 2-DG uptake stimulated by insulin alone, significant correlations existed between GLUT-4 protein content and 2-DG uptake stimulated either by contractions alone (r = 0.950) or by insulin and contractions in combination (r = 0.992). These results suggest that the differences in maximally stimulated glucose transport activity among the three fiber types may be related to differences in their content of GLUT-4 protein.
Henriksen
E J
EJ
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
Bourey
R E
RE
Rodnick
K J
KJ
Koranyi
L
L
Permutt
M A
MA
Holloszy
J O
JO
D000199:Actins / Q000235:genetics; D000818:Animals; D001693:Biological Transport, Active; D004558:Electric Stimulation; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009119:Muscle Contraction; D009132:Muscles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009928:Organ Specificity; D012313:RNA / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains
D000199:Actins; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D012313:RNA; D005947:Glucose