Oral Vanadate Reduces Na⁺-Dependent Glucose Transport in Rat Small Intestine

The effects of oral vanadate supplementation on intestinal morphometry and glucose transport were examined in STZ-induced diabetic and age-matched control male Sprague-Dawley rats. Animals received 0.1 mg/ml vanadium pentoxide in their drinking water over 14 days. Vanadate reduced intestinal glucose maximal transport capacity in both diabetic and control animals. In jejunum tissue, this decrease in glucose absorption was a direct consequence of downregulation of the glucose carrier and was not related to changes in mucosal morphometry. In the ileum tissue of control animals, the vanadate-induced decrease in glucose maximal transport capacity occurred in conjunction with an increase in carrier affinity and mucosal morphometric measurements. In the ileum tissue of diabetic animals, the vanadate-induced decrease in glucose maximal transport capacity occurred with a decrease in mucosal morphometric measurements. Na⁺-K⁺-adenosine triphosphatase activity was affected by vanadate only in diabetic animals. These results demonstrate that oral vanadate supplementation results in downregulation of the small intestinal sodium-dependent glucose carrier in both diabetic and nondiabetic rats. Furthermore, the vanadate effect may be occurring at the cellular level.