Diabetes, Vol 35, Issue 11 1200-1205, Copyright © 1986 by American Diabetes Association
Effect of aldose reductase inhibitor (sorbinil) on integration of polyol pathway, pentose phosphate pathway, and glycolytic route in diabetic rat lens
AM Gonzalez, M Sochor, JS Hothersall and P McLean
This study examines the effect of an aldose reductase inhibitor (sorbinil)
on the flux of specifically labeled glucose through alternative pathways of
metabolism in the lens of normal and diabetic rats 1 wk after the induction
of diabetes with alloxan. In the diabetic rat lens, there was an apparent
increase in the flux of glucose through the pentose phosphate pathway
(PPP), as measured by the difference in the yields of 14CO2 from
[1-14C]glucose and [6-14C]glucose [C1-C6], this value was 0.087 +/- 0.005
and 0.263 +/- 0.034 mumol X g lens-1 X h (mean + SE of 6 values) for
control and diabetic rats, respectively; sorbinil treatment decreased the
values to 0.065 +/- 0.008 and 0.171 +/- 0.028, respectively. With glucose
tritiated on carbon 2 or 3, it has been shown that the flux of glucose
through the polyol route is increased, whereas the flux through the
glycolytic pathway is decreased in the diabetic rat lens; both are restored
toward normal in the sorbinil-treated diabetic group. These results suggest
that the dual effects of diabetes in increasing the lens content of glucose
and glucose 6-phosphate and the flux of glucose in the polyol pathway will
result in an increased utilization of NADPH and production of NADH, factors
favoring the flow of glucose through the PPP and restricting the glycolytic
route in the diabetic rat lens. The inhibition of aldose reductase by
sorbinil tends to normalize the redox state of the nicotinamide
nucleotides, reimposing the NADPH limitation on the PPP and increasing the
availability of NAD+ for the glycolytic route.