Regulation of glucose transporters (GLUT-1 and GLUT-3) in human retinal endothelial cells

The regulation of glucose transporters (GLUT-1 and GLUT-3), in terms of both mRNA and protein, in human retinal endothelial cells was investigated. The cells responded within 1 h of exposure to 5 mM glucose with an increase in the level of GLUT-3 mRNA that was due to an increase in the transcription of the 4.1 kb mRNA of the gene for GLUT-3. In the absence of glucose, the gene for GLUT-1 was not transcribed but the level of GLUT-3 mRNA was increased in these conditions and this was the result of an increase in the transcription of the 4.1 kb mRNA. The level of GLUT-1 and GLUT-3 mRNA was maximal when the cells were exposed to 15 mM glucose. These results are discussed in the light of the glucose regulatory potential of the retinal microvasculature and the implications that this may have for the mechanisms of diabetic retinopathy.