Journal: Molecular Metabolism

Article Title: Inducible deletion of skeletal muscle AMPKα reveals that AMPK is required for nucleotide balance but dispensable for muscle glucose uptake and fat oxidation during exercise

doi: 10.1016/j.molmet.2020.101028

Figure Lengend Snippet: Normal insulin action despite acute deletion of catalytic AMPK function in skeletal muscle. A–B: 3 weeks after the last tamoxifen injection, control and AMPKα imdKO mice were fasted for 5 h before they were given an intraperitoneal injection of glucose (2 g/kg body weight) dissolved in a 0.9% saline solution. Blood was sampled from the tail vein and analyzed for glucose concentration by a glucometer before (0 min) and 20, 40, 60, 90, and 120 min after injection. Plasma insulin levels were determined at 0, 20, and 40 min by using an insulin ELISA assay (n = 10–12). C: For the insulin tolerance test (ITT), mice were fasted for 2 h, and insulin was injected intraperitoneally (1 U/kg body weight, Actrapid, Novo Nordisk, Bagsværd, Denmark). Tail vein blood glucose concentration was measured before (0 min), 20, 40, and 60 min after injection (n = 10–12). D–E: Isolated EDL and soleus muscles from control and AMPKα imdKO mice were incubated for 30 min in the absence (basal) or presence of 100 μU/ml and 10,000 μU/ml insulin, and muscle glucose uptake was determined by measuring the accumulation of intracellular [ 3 H]-2-deoxyglucose (2DG) (n = 6–8). F–H: Key insulin signaling intermediates in EDL muscle from control and AMPKα imdKO mice were investigated by immunoblotting and are given as representative immunoblots. Data are given as means ± SEM. Two-way RM ANOVA was used to investigate the effect of genotype and time (GTT and ITT) or genotype and insulin concentrations (2DG uptake). ###p ≤ 0.001 for significantly different from basal (0 min). ∗∗p ≤ 0.01 and ∗∗∗p ≤ 0.001 for significantly different compared to basal. §§p ≤ 0.01 and §§§p ≤ 0.001 for significantly different from 100 μU/ml. Line indicates main effect.

Article Snippet: In summary, excised soleus muscles from anesthetized mice were mounted at resting tension (∼5 mN) in vertical incubation chambers (Radnoti, Monrovia, CA) containing 30 °C carbogenated (95% O 2 and 5% CO 2 ) KRB supplemented with 5 mM glucose, 2% fat-free BSA, and 0.5 mM palmitate.

Techniques: Injection, Control, Saline, Concentration Assay, Clinical Proteomics, Enzyme-linked Immunosorbent Assay, Isolation, Muscles, Incubation, Western Blot