Plasma substrate analyses
BLOOD
Blood samples were collected in EDTA, NaF, and serum tubes. After collection, EDTA and NaF tubes were stored on ice and spun down at 4 °C for 10 minutes at 1300 RCF. Serum tubes were stored at room temperature for at least 30 minutes to allow coagulation and were thereafter spun down at 21 °C for 10 minutes at 1300 RCF. Blood plasma and serum were collected and stored at −80 °C until further analyses. Plasma glucose (Horiba, Montpellier, France), free fatty acids (WAKO, Neuss, Germany), and triglycerides (Sigma, St Louis, USA) concentrations were measured by means of a colorimetric analysis using a Cobas Pentra C400 analyzer (Horiba, Montpellier, France). Plasma insulin concentrations were measured by means of an ELISA (Crystal Chem, Elk Grove Village, USA).