Statstrip xpress

Blood, isolated at baseline and 1, 2, 4, and 6 h post-LPS injection by tail bleed, was placed onto a glucose StatStrip Xpress (Nova Biomedical, Waltham, MA, United States). Glucose levels were subsequently quantified using a glucometer.

Energy expenditure was measured and recorded using the Columbus Instruments Oxymax system (Columbus, OH US) according to the manufacturer’s instructions. Mice were randomly allocated to the chambers and they had free access to food and water throughout the experiment with the exception of fasting experiments. An initial 18–24 hr acclimation period was disregarded for all the experiments. Once mice were acclimated to the chamber, the composition of the influx gas was switched from 21% O₂ to 10% O₂ using a PEGAS mixer (Columbus Instruments). For maximum exertion testing, mice were allowed to acclimatize to the enclosed treadmill environment for 15 min before running. The treadmill was initiated at five meters/min and the mice warmed up for 5 min. The speed was increased up to 27 meters/min or exhaustion at 2.5 min intervals on a 15° incline. Exhaustion was defined as the third time the mouse refused to run for more than 3–5 s or when was unable to stay on the treadmill. Blood glucose and lactate levels were measured before and after exertion using a StatStrip Xpress (nova biomedical, Street-Waltham, MA US) glucose and lactate meters.

Type 1 diabetes was induced in 10- to 12-week-old male C57BL6/J mice using multiple low doses of streptozotocin (STZ). On each of five consecutive days, mice were fasted for 6 h and then given an intraperitoneal injection of 55 mg/kg STZ freshly dissolved in sodium citrate buffer (pH 4.5). Blood glucose was measured after a 3 h fast by weekly tail vein sampling (Stat Strip Xpress, Nova Biomedical, Whaltham, MA, U.S.A.) after the STZ injections. Mice achieving a consistent fasting blood glucose level of >16 mmol/L at 2 weeks after STZ were considered diabetic. After becoming diabetic, fasting blood glucose levels were maintained within the target range (20–28 mmol/L), with 0.4U of long-acting insulin (Protophane, Novo Nordisk, Baulkham, Australia) given by subcutaneous injection as required. Plasma was collected from the tail vein to measure HbA1c (DCA Vantage Analyzer, Siemens Healthcare Diagnostics, Tarrytown, NY, U.S.A.) prior to IRI surgery (week 8) and at the end of the study (week 12). Diabetic mice with an HbA1c >8% at week 8, were used for sham or ischemia–reperfusion injury (IRI) surgery and randomly assigned to treatment groups.

Blood samples were analyzed for arterial and mixed venous blood gasses (pO₂, pCO₂, pH, HCO₃⁻, O₂ saturation and BE) using the Cobas-b-221 blood gas system (Roche Diagnostics, Indianapolis, IN). Lactate was analyzed by Stat Strip Xpress (Nova Biomedical Corporation, Waltham, MA). Samples for complete blood count, coagulation tests, blood chemistry (electrolytes, CPK, liver enzymes [Bilirubin, AST, ALT, ALP, GGT], renal function tests [Urea, Creatinine], and glucose), and total serum cortisol were analyzed by standard clinical laboratory analysis. Urine was collected at each time point throughout the experiment.