Figure 7: SUR2 Regulates Glucose Uptake and GLUT4 Localization in Adult Hearts

(A) Insulin stimulation significantly increased 2-deoxyglucose (2DG) uptake in both MCM Cre– and MCM Cre+ cardiomyocytes. 2DG levels were significantly elevated in MCM Cre+ cardiomyocytes compared with MCM Cre– cardiomyocytes post-insulin stimulation (n >7). *p < 0.05. (B) Thirty minutes post-insulin injection MCM Cre+ hearts showed increased GLUT4 in the plasma membrane fraction of prepared microsomes (black arrow) (n ≥4 per genotype). Total protein was used as a loading control (LC). Relative sarcolemmal GLUT4 is represented as the ratio of membrane fraction GLUT4 over total GLUT4. *p < 0.03. (C) Insulin receptor (INSR) protein levels were unchanged between MCM Cre– and MCM Cre+ hearts (n = 6); LC, loading control. (D, E) Thirty min post-insulin injection MCM Cre+ hearts showed a significant elevation (black arrow) in the ratio of phosphorylated AKT (pAKT) (Thr308)/AKT and phosphorylated AKT(Ser473)/AKT (n = 4). *p < 0.001 Thr308, *p = 0.003 Ser473. (F) Thirty and 60 min post-insulin injection, MCM Cre+ hearts showed a significant elevation in the ratio of phosphorylated FOXO1 (pFOXO1) (Thr24)/FOXO1 (black arrows) (n = 4). *p < 0.0001. -Ins = without insulin; +Ins = plus insulin; AU = arbitrary units; other abbreviations as in Figures 1 and 2.

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