Effect of rapid alteration in glucose concentration and insulin on thymidine uptake in bovine retinal capillary endothelium.

The effect of insulin and rapid changes in glucose concentration on bovine retinal capillary endothelium (BRCE) was examined by use of tissue culture and 3H-thymidine incorporation. In the absence of insulin, no effect on thymidine uptake by BRCE was observed when glucose concentration was rapidly altered, either increased or decreased. The stimulating effect of insulin on retinal capillary endothelin was more pronounced in log-phase cells than in stationary-phase cells. The extent of stimulation by insulin decreased with increasing glucose concentrations. This effect was not observed when osmotic pressure was increased by mannitol. The results of our experiments make it unlikely that altered osmotic stress, rapidly changing or abnormal glucose levels would be primarily responsible for altered endothelial activity.