Na(+)-D-glucose cotransporter in muscle capillaries increases glucose permeability.
By immunohistochemistry, we demonstrated the localization of the Na(+)-D-glucose cotransporter SGLT1 in capillaries of rat heart and skeletal muscle, but not in capillaries of small intestine and submandibular gland. mRNA of SGLT1 was identified in skeletal muscle and primary cultured coronary endothelial cells. The functional relevance of SGLT1 for glucose transport across capillary walls in muscle was tested by measuring the extraction of D-glucose from the perfusate during non-recirculating perfusion of isolated rat hindlimbs. In this model, D-glucose extraction from the perfusate is increased by insulin which accelerates D-glucose uptake into myocytes by increasing the concentration of glucose transporter GLUT4 in the plasma membrane. The insulin-induced increase of D-glucose extraction from the perfusate was abolished after blocking SGLT1 with the specific inhibitor phlorizin. The data show that SGLT1 in capillaries of skeletal muscle is required for the action of insulin on D-glucose supply of myocytes.
Elfeber
Katrin
K
Institut für Anatomie und Zellbiologie der Bayerischen Julius-Maximilians-Universität, Koellikerstrasse 6, 97070 Würzburg, Germany.
Stümpel
Frank
F
Gorboulev
Valentin
V
Mattig
Sabine
S
Deussen
Andreas
A
Kaissling
Brigitte
B
Koepsell
Hermann
H
D000818:Animals; D001692:Biological Transport; D015153:Blotting, Western; D002196:Capillaries / Q000378:metabolism*; D002199:Capillary Permeability; D002462:Cell Membrane / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D007150:Immunohistochemistry; D007328:Insulin / Q000378:metabolism; D007421:Intestine, Small / Q000098:blood supply; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism; D009132:Muscles / Q000098:blood supply*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D010477:Perfusion; D016133:Polymerase Chain Reaction; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051269:Sodium-Glucose Transporter 1; D013363:Submandibular Gland / Q000098:blood supply; D013997:Time Factors
D051275:Glucose Transporter Type 4; D007328:Insulin; D008562:Membrane Glycoproteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; C495676:Slc5a1 protein, rat; D051269:Sodium-Glucose Transporter 1; D005947:Glucose