Experimental streptozotocin-induced diabetes and intestinal glucose metabolism in the rat, in vivo and in vitro

The intestine has a high glycolytic activity, but its metabolic role could be altered in diabetes mellitus. The aim of the present work was to investigate in vivo the glucose retained and the lactate produced by the intestine of normal and diabetic rats and in vitro the effect of different arterial glucose concentrations on glucose utilization and lactate, alanine, and pyruvate production in normal and diabetic rats when the glucose is supplied to the intestine exclusively via the vascular route. In vivo, the normal and diabetic rats retained similar percentages of the arterially supplied glucose (14.7±3.2 and 12.6±2.4, respectively). In vitro, when the preparations were perfused under hyperglycemic conditions, the glucose consumed, as a fraction of the quantity infused, was significantly lower (P<0.05) in the diabetic (247.0±22.8 µmol/mmol infused glucose) than in normal (315.0±16.3 µmol/mmol infused glucose) rats. The lactate produced was significantly higher in diabetic than in normal rats whether the preparations were perfused under isoglycemic (P<0.01; 1916.4±124.0 vs 1284±67.7 µmol/mmol consumed glucose) or hyperglycemic (P<0.05; 1356.4±199.7 vs 898.0±87.3 µmol/mmol consumed glucose) conditions. There was significantly (P<0.05) greater alanine release from the diabetic (123.7±21.8 µmol/mmol consumed glucose) than from the normal (40.7±10.3 µmol/mmol consumed glucose) rat preparations perfused under isoglycemic conditions.