NA-DEPENDENT GLUCOSE-UPTAKE AND COLLAGEN-SYNTHESIS BY CULTURED BOVINERETINAL PERICYTES()

This study was performed to clarify the presence of sodium-dependent g lucose uptake and its role in the synthesis of type IV and type VI col lagen by cultured bovine retinal pericytes. The glucose uptake by reti nal pericytes and retinal endothelial cells was measured using H-3-D-g lucose in the presence or absence of sodium. Glucose uptake in the pre sence of sodium was twice as high as that observed in the presence of phlorizin and sodium or in the absence of sodium. Sodium-dependent glu cose uptake was observed at different sodium concentrations, and its h alf-maximal stimulation occurred at 48 mM. These findings were not obs erved in retinal endothelial cells. Levels of type IV and type VI coll agen produced by retinal pericytes were significantly increased at glu cose concentrations higher than 20 mM. Phlorizin decreased both collag en synthesis and glucose consumption by retinal pericytes incubated wi th 30 mM of glucose to the levels observed with 5 mM of glucose. These data suggest that sodium-dependent glucose uptake is present in retin al pericytes and that excessive glucose entry into the cell is an impo rtant factor for overproduction of collagen. Phlorizin normalized the synthesis of type IV and type VI collagen with decreasing glucose cons umption under high glucose conditions. (C) 1997 Elsevier Science B.V.