Insulin-Like Effects of Vanadate in Isolated Rat Adipocytes*

Abstract

Vanadate has been shown to have a number of insulin-like effects in various cells, including isolated rat adipocytes. In the present study we compared the activities of vanadate and insulin in isolated fat cells using a number of different assays of insulin-like activity. Both insulin and vanadate stimulated [2-3H]glucose incorporation into fat cell lipid in a dose-dependent manner, but the maximal effect of vanadate was markedly greater than that of insulin. At 10(-2) M vanadate the effect was 3-4 times as great as the maximal effect of insulin. This effect was dependent on specific glucose transport. Combinations of insulin and vanadate were not more effective than vanadate alone. Vanadate also produced antilipolysis with an effect somewhat greater than that of insulin. Using [U-14C]glucose both vanadate and insulin stimulated 14CO2 production and [14C]glucose incorporation into lipid, and again the effect of vanadate was greater than that of insulin. Vanadate had a greater effect on 14CO2 production than on [14C]glucose incorporation into lipid. When [1-14C]glucose was used vanadate again had a significantly greater effect on 14CO2 production than did insulin, but when [6-14C]glucose was used the effects of vanadate and insulin were equal. These results demonstrate that vanadate has insulin-like effects in isolated fat cells, but it selectively stimulates certain pathways to a greater extent than does insulin. The greater effect of vanadate than insulin appears to be primarily on the pentose phosphate shunt, suggesting that this agent may be useful for examination of this intracellular pathway in fat cells.

Long-Term Acting and Orally Active Vanadyl-Methylpicolinate Complex with Hypoglycemic Activity in Streptozotocin-Induced Diabetic Rats.

“…Among the four complexes, VU-MPA was found to have the highest partition coefficient. Effect of vanadyl complexes on FFA release from isolated rat adipocytes treated with epinephrine To evaluate in vitro insulin mimetic activity of four vanadyl complexes, we examined the effect of these complexes on FFA release from isolated rat adipocytes treated with epinephrine in the absence of glucose as proposed before [16,22,28,38,39]. Figure 2 summarizes the effects of the four vanadyl complexes, comparing with that of VS as a positive control.…”

The effect of vanadyl treatment on vascular responsiveness of streptozotocin-diabetic rats

“…These include enhancement of glucose transport and oxidation in rat adipocytes [17,18] and skeletal muscle [19,20], stimulation of pentose phosphate pathway [21] and glycogen synthase activity in rat adipocytes [22], enhancement of glycogen synthesis in the liver and diaphragm [23], inhibition of lipolysis [24] and activation of lipogenesis in rat adipocytes [25] and reduction of insulin requirement in spontaneously diabetic (BB Wistar) rats [26]. It has also been shown that vanadium compounds, both in the vanadate and vanadyl forms, lower plasma glucose and prevent the decline in cardiac performance [26][27][28][29][30] due to diabetes when administered to intact experimentally-induced diabetic rats.…”

Insulin-Like Effects of Vanadium Pentoxide (V2O5) on Glucose Consumption in Primary Human Fibroblasts

“…If left untreated, DM can lead to a complication of diabetes. It is well known that vanadium compounds have insulin-like effects in vivo [1][2][3][4][5][6][7][8] and in vitro [9,10], but medicinally-useful vanadium compounds have not yet been developed. One of reasons is that vanadium is cytotoxic at high concentrations.…”