Characterization of [2-3H]deoxy-D-glucose uptake in retina and retinal pigment epithelium of normal and diabetic rats.
The outer blood-retinal barrier which results from the tight junctions between retinal pigment epithelial cells (RPE) restricts the flow of nutrients reaching the retina. We characterize the transport of [2-3H]deoxy-D-glucose (2-DG) across isolated mammalian neural retina and RPE in terms of their kinetics constants. In addition, the effect of insulin on glucose transport was studied by using streptozotocin-induced diabetic rats. RPE accumulates 2-DG by a temperature-sensitive and energy-dependent complex kinetics mechanism. The retina takes up 2-DG by an energy and Na(+)-dependent saturable system with an apparent Km of 2 mM. Insulin induced an increase of 2-DG uptake by normal retina. The retina of diabetic rats shows lower levels of 2-DG accumulation. These levels can be returned to the normal ones by exposure to insulin. Although insulin does not affect, significantly, 2-DG accumulation by RPE, 2-DG uptake of RPE from diabetic rats shows a normal saturable kinetics with an apparent Km of 20 mM. Those findings suggest the presence of different types of glucose transporters in retina and RPE. Insulin-sensitive glucose transport in retina might be involved in the manifestation of diabetic retinopathy.
Vilchis
C
C
Instituto de Fisiología Celular, UNAM, México.
Salceda
R
R
D000818:Animals; D000963:Antimetabolites / Q000378:metabolism* / Q000493:pharmacokinetics; D003847:Deoxyglucose / Q000378:metabolism* / Q000493:pharmacokinetics; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D010857:Pigment Epithelium of Eye / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D012160:Retina / Q000187:drug effects / Q000378:metabolism*
D000963:Antimetabolites; D007004:Hypoglycemic Agents; D007328:Insulin; D003847:Deoxyglucose