Diabetes increases facilitative glucose uptake and GLUT2 expression at the rat proximal tubule brush border membrane.
The mechanism of renal glucose transport involves the reabsorption of filtered glucose from the proximal tubule lumen across the brush border membrane (BBM) via a sodium-dependent transporter, SGLT, and exit across the basolateral membrane via facilitative, GLUT-mediated, transport. The aim of the present study was to determine the effect of streptozotocin-induced diabetes on BBM glucose transport. We found that diabetes increased facilitative glucose transport at the BBM by 67.5 % (P < 0.05)--an effect that was abolished by overnight fasting. Western blotting and immunohistochemistry demonstrated GLUT2 expression at the BBM during diabetes, but the protein was undetectable at the BBM of control animals or diabetic animals that had been fasted overnight. Our findings indicate that streptozotocin-induced diabetes causes the insertion of GLUT2 into the BBM and this may provide a low affinity/high capacity route of entry into proximal tubule cells during hyperglycaemia.
Marks
Joanne
J
Department of Physiology and Centre for Nephrology, Royal Free and University College Medical School, London, UK. marks@rfc.ucl.ac.uk
Carvou
Nicolas J C
NJ
Debnam
Edward S
ES
Srai
Surjit K
SK
Unwin
Robert J
RJ
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D015153:Blotting, Western; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000473:pathology; D005947:Glucose / Q000378:metabolism*; D051273:Glucose Transporter Type 2; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000473:pathology; D007687:Kidney Tubules, Proximal / Q000378:metabolism* / Q000473:pathology; D007700:Kinetics; D008297:Male; D018613:Microscopy, Confocal; D008871:Microvilli / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis*; D009929:Organ Size / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D001786:Blood Glucose; D051273:Glucose Transporter Type 2; D009004:Monosaccharide Transport Proteins; D005947:Glucose