C. Vilchis et R. Salceda, CHARACTERIZATION OF [2-H-3] DEOXY-D-GLUCOSE UPTAKE IN RETINA AND RETINAL-PIGMENT EPITHELIUM OF NORMAL AND DIABETIC RATS, Neurochemistry international, 28(2), 1996, pp. 213-219
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-H-3
]deoxy-D-glucose (2-DG) across isolated mammalian neural retina and RP
E in terms of their kinetics constants. In addition, the effect of ins
ulin on glucose transport was studied by using streptozotocin-induced
diabetic rats. RPE accumulates 2-DG by a temperature-sensitive and ene
rgy-dependent complex kinetics mechanism. The retina takes up 2-DG by
an energy and Na+-dependent saturable system with an apparent K-m 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. Alt
hough insulin does not affect, significantly, 2-DG accumulation by RPE
, 2-DG uptake of RPE from diabetic rats shows a normal saturable kinet
ics with an apparent K-m 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 manife
station of diabetic retinopathy.