[Effects of vanadate on glucose metabolism of the streptozotocin-diabetic rat lens].

The effects of oral administration of vanadate, an oxidized form of vanadium, on glucose metabolism of the lens were studied in 5-week-old male Sprague-Dawley rats rendered diabetic with streptozotocin (50 mg/kg, intraperitoneal injection). The rats were given 0.2g/l NaVO3-5 g/l NaCl solution in drinking water ad libitum for 2 weeks and biochemical parameters in their lenses were determined. Blood glucose levels significantly decreased in the vanadate-administered diabetic rats (DM-V group), compared with the diabetic rats given no vanadate (DM group). In the DM-V group, significant decreases were observed in lens contents of glucose and sorbitol without significant decrease in fructose content, compared with the DM group. In the former group, aldose reductase activity was not decreased, but sorbitol dehydrogenase (SDH) activity was significantly increased, compared with the latter group. These results suggest that oral administration of vanadate may decrease sorbitol content in the diabetic rat lens by an acceleration of the sorbitol pathway to fructose accompanied by increase in SDH activity.