Elevated GLUT 1 level in crude muscle membranes from diabetic Zucker rats despite a normal GLUT 1 level in perineurial sheaths.
Recently, we demonstrated that approximately 60% of GLUT 1 in a crude membrane fraction of rat skeletal muscle originates from perineurial sheaths. To study the in vivo regulation of GLUT 1 expression in different tissues in muscles, we measured the level of GLUT 1 in crude muscle membranes and in perineurial sheaths in diabetic (fa/fa) Zucker rats and lean controls, with and without metformin treatment. The GLUT 1 concentration in perineurial sheaths was identical in all four groups of rats, both when measured by quantitative immunofluorescence and by immunoblotting and densitometry. In a fraction of crude membranes of soleus muscles GLUT 1 expression was more than two-fold higher in (fa/fa) rats than in lean controls (p < 0.005). Metformin treatment significantly elevated GLUT 1 in control rats (p < 0.05) and tended to decrease GLUT 1 in diabetic rats (p < 0.075). The expressions of GLUT 1 and GLUT 4 in crude muscle membranes were inversely correlated (p < 0.01), and GLUT 1 expression correlated positively with fasting glucose (p < 0.05). In conclusion, GLUT 1 expression in perineurial sheaths is unaffected by alterations in glucose homeostasis and by the genes responsible for obesity and diabetes in the Zucker rat. GLUT 1 expression in a crude membrane fraction of soleus muscle is increased in the diabetic animals, likely due to an increased expression in muscle cells proper.
Handberg
A
A
Department of Medical Physiology, Panum Institute, University of Copenhagen, Denmark.
Kayser
L
L
Høyer
P E
PE
Micheelsen
J
J
Vinten
J
J
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003920:Diabetes Mellitus / Q000097:blood / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005267:Femoral Nerve / Q000378:metabolism*; D019270:Fructosamine; D051272:Glucose Transporter Type 1; D006595:Hexosamines / Q000097:blood; D007328:Insulin / Q000097:blood; D008297:Male; D008687:Metformin / Q000494:pharmacology; D008970:Molecular Weight; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism*; D009186:Myelin Sheath / Q000378:metabolism*; D009765:Obesity; D051381:Rats; D011924:Rats, Zucker; D012016:Reference Values
D001786:Blood Glucose; D051272:Glucose Transporter Type 1; D006595:Hexosamines; D007328:Insulin; D009004:Monosaccharide Transport Proteins; C495679:Slc2a1 protein, rat; D019270:Fructosamine; D008687:Metformin