Glucose, Insulin, and Pyruvate Tolerance Tests

Glucose (GTT), insulin (ITT) and pyruvate (PTT) tolerance tests were performed as described previously [37 (link)] after the mice were challenged with HFD and treated with carvedilol for 4 weeks. Body weight were 48.98 ± 1.22 g for HFD-fed + vehicle treatment cohort (n = 6) and 47.62 ± 0.91 g for HFD-fed + carvedilol treatment cohort (n = 6), P = 0.392. For GTT and PTT, mice were fasted overnight for 16 hours with water ad libitum provided. After measurement of fasted glucose levels, mice were intraperitoneally injected with a glucose solution (1.5 g/kg body weight) or sodium pyruvate solution (2 g/kg body weight) in normal saline. For ITT, mice were fasted for 2 hours and provided with water ad libitum. After measurement of basal glucose levels, 0.75 U/kg body weight of regular insulin (Humulin® U-100, Eli Lilly and Co., IN, USA) in normal saline was administered intraperitoneally. Blood samples were taken from a tail nick at 0, 15, 30, 60, 90, 120, and 150 minutes after injection and glucose levels were measured. The area under the curve (AUC) was determined to quantify the glucose, pyruvate and insulin tolerance.