title: Stimulation of glucose transport in L6 muscle cells by long-term intermittent stretch-relaxation.
abstract: Skeletal muscle stretch increases resting metabolism and causes hypertrophy. We have examined the effect of mechanical stretch in vitro on glucose transport activity and transporter contents in L6 muscle cells. Long-term (24-48 h) stretch-relaxation (25% maximal elongation at 30 cycles per min) of cell monolayers significantly increased glucose uptake by 1.6- to 2-fold in myotubes but not in myoblasts. The presence of serum was required for the stretch-relaxation induced increase in glucose uptake. Cycloheximide inhibited the mechanical stimulation of glucose uptake, and the latter response was not additive to the stimulatory effect of long-term exposure to insulin. GLUT1 and GLUT4 glucose transporter contents were not changed in total cell membranes from mechanically stimulated cells relative to controls. These results indicate that mechanical stimulation through passive stretch may be an important regulation of nutrient uptake in fetal myotubes independent of innervation.
authors.affiliation: Division of Cell Biology, Hospital for Sick Children, Toronto, Ont., Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Mitsumoto
authors.forename: G P
authors.initials: GP
authors.lastname: Downey
authors.forename: A
authors.initials: A
authors.lastname: Klip
mesh_terms: D000818:Animals; D001692:Biological Transport; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000494:pharmacology; D009004:Monosaccharide Transport Proteins / Q000032:analysis*; D009124:Muscle Proteins; D009126:Muscle Relaxation / Q000502:physiology*; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D010812:Physical Stimulation; D051381:Rats; D013997:Time Factors
chemical_list: D016895:Culture Media, Serum-Free; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495679:Slc2a1 protein, rat; C495694:Slc2a4 protein, rat; D003513:Cycloheximide; D005947:Glucose