Changes of Blood Hormones and Metabolites upon Intravenous Glucose Infusion in Steers

Abstract

Three Korean steers aged 13 months (body wt. 300±10.3 kg) were infused with three treatment solutions (0, 50, or 100 mg of glucose/kg body wt.) through a jugular vein catheter and were allotted into a 3  3 Latin square design. Blood samples were collected at 0 (just before infusion), 5 min intervals until 30 min, and 40, 50, 60, 90, and 120 min after glucose infusion. The blood glucose concentration immediately increased upon the infusion of glucose through the jugular vein and decreased to the level of the control (0.9% saline) at 30 min after infusion. The insulin concentration of the blood instantly increased with glucose infusion and was maintained until 10 min after infusion, after which it slowly decreased until 30 min after infusion in the 50mg treatment. In the 100 mg treatment, however, the concentration of insulin showed two peaks (119.6 μU/ml at 5 min and 176.6μU/ml at 15 min after infusion) and then precipitously decreased at 20 min after infusion. From the pattern of secretion of insulin upon the intravenous infusion of glucose, we found that the amount of insulin secreted at once from the pancreas into the bloodstream was about 120μU/ml of blood and the secretion of insulin to above 130mg/100 ml of blood glucose reacted with a stepwise manner