The effect of glucose and insulin concentration on type IV collagen biosynthesis by bovine retinal capillary endothelial cells in vitro.

Qualitative and quantitative analyses of type IV collagen, newly synthesized by cultured retinal capillary endothelial cells were carried out. After 24-hour incubation in high glucose (25 mM) media with 14C proline there was less type IV collagen synthesis than after incubation in 5.6 mM glucose media. Insulin stimulated the biosynthesis of type IV collagen in both low and high glucose concentrations. The stimulating effect of insulin (on the biosynthesis of type IV collagen) was still observed after inhibition of cell growth with hydroxyurea. High ambient glucose and the insulin effect could play a role in the structural changes observed in diabetic retinal microvascular basement membranes.