Metabolic effect of sodium selenite: Insulin-like inhibition of glucagon-stimulated glycogenolysis in the isolated perfused rat liver

Authors


Abstract

Selenium, an essential trace element, has been shown to decrease plasma glucose concentrations of diabetic rats. To study the short-term effects of selenium on hepatic carbohydrate metabolism, isolated perfused livers of fed Sprague-Dawley rats were continuously infused with sodium selenite for 90 minutes. This resulted in an immediate elevation of selenium in the effluent perfusate (3.3 ± 0.1, 16.1 ± 0.4, 30.3 ± 1.6, and 118.9 ± 0.8 μmol/L at infusion of 10,50, 100, and 500 μmol/L sodium selenite, respectively). Basal hepatic glucose production decreased in a dose-dependent manner within 60 minutes of low-dose sodium selenite infusion (10: 0.60 ± 0.20, 50: 0.21 ± 0.40, and 100 ümol/L: 0.21 ± 0.09 μmol/L · min−1 · g−1 liver; P < .05 vs. zero time), while it was transiently increased by 500 μmol/L sodium selenite (1.11 ± 0.18 μmol · min<1> · g−1 liver; P < .05). Glucagon-stimulated glycogenolysis was suppressed by 50% (P < .05) at 1.8 nmol/ L insulin and by 90% (P < .001) at 10 μmol/L sodium selenite. That selenium concentration did not affect glutathione peroxidase activities in liver and perfusate erythrocytes within 60 minutes. Toxic effects of high-dose selenite (500 μmol/L), but not of low-dose selenite (10 μmol/L) infusion, were indicated by increased hepatic glucose (P < .05), lactate (P < .01), and lactate dehydrogenase (P < .001) release as well as histologically by degeneration and necrosis of periportal hepatocytes. In conclusion, low-dose selenite exerts a potent insulinlike effect on hepatic glycogenolysis in vitro by counteracting glucagon action, whereas high-dose selenite may severely impair liver function. (HEPATOLOGY 1995; 22:169–174.)

Ancillary