Insulin-like growth factor-I-stimulated glucose transport in myotubes derived from chicken muscle satellite cells.
The effects of insulin and insulin-like growth factor-I (IGF-I) on glucose transport were compared in myotubes derived from chicken breast muscle satellite cells in vitro. Myotubes were incubated (for 0.5 or 4 h) with or without glucose in the presence or absence of insulin or IGF-I. Glucose uptake was subsequently measured by the incorporation of 2-[1,2-3H(N)] deoxy-D-glucose ([3H]2DG) in glucose-free medium (10 min at 20 degrees C). Glucose uptake was almost completely abolished by the addition of cytochalasin B or phloretin. It was increased by a decrease in glucose concentration in the incubation medium. Insulin (5 mg/l) stimulated [3H]2DG uptake to a maximum of 43 +/- 10% above basal after 30-min incubation and 101 +/- 15% after 4-h incubation. IGF-I and insulin at equimolar concentrations (25 micrograms/l and 20 micrograms/l respectively) were almost equipotent after 0.5 h but after 4-h incubation IGF-I was 17-fold more potent, suggesting that this 'late' effect was mediated through the IGF-I receptor. Incubation with cycloheximide suggested that the effect of IGF-I involved increased protein synthesis. The results suggest that chicken myotubes express a glucose transporter which is regulated by IGF-I and glucose concentration. However, they do not appear to express a typical insulin-responsive transport system.
Duclos
M J
MJ
INRA, Station de Recherches Avicoles, Endocrinologie de la Croissance et du Métabolisme, Nouzilly, France.
Chevalier
B
B
Le Marchand-Brustel
Y
Y
Tanti
J F
JF
Goddard
C
C
Simon
J
J
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D002478:Cells, Cultured; D002645:Chickens; D003513:Cycloheximide / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D003847:Deoxyglucose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008297:Male; D009132:Muscles / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010693:Phloretin / Q000494:pharmacology
D007328:Insulin; D003571:Cytochalasin B; D007334:Insulin-Like Growth Factor I; D003513:Cycloheximide; D003847:Deoxyglucose; D005947:Glucose; D010693:Phloretin