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. 2019 Mar 27;10:189. doi: 10.3389/fphys.2019.00189

FIGURE 2.

FIGURE 2

Acute treatment with GGF2 stimulates the regulation of glucose transport via the ErbB receptors in healthy adult cardiac myocytes. (A) GGF2 treatment stimulates GLUT4 trafficking to the cell surface. Top panel: representative Western blot. Bottom Panel: Mean ± SE of cell surface GLUT4 protein content; values normalized to basal (n = 3-8/group); #P < 0.05 vs. basal. Methods: Photolabeled biotinylated assay in isolated rat ventricular myocytes incubated without (i.e., basal, −) or with insulin (+) or incremental dose of GGF2 (i.e., 1, 10, and 100 ng/ml). L, Labeled (cell surface fraction); UL, unlabeled (intracellular fraction). (B) ErbB receptor blockade (afatinib) blunts GGF2-stimulated GLUT4 translocation. Top panel: representative Western blot. Bottom Panel: Mean ± SE of cell surface GLUT4 protein content; values normalized to basal (n = 3–8/group); #P < 0.05 vs. basal; ∗P < 0.05 vs. GGF2. Methods: Photolabeled biotinylated assay in isolated rat ventricular myocytes incubated without (i.e., basal, −) or with (+) afatinib for 1 h prior to incubation with insulin or GGF2 (100 ng/ml) for 1 h. (C) GGF2 increases total GLUT4 expression. Top panel: representative Western blot. Bottom panel: Mean ± SE of protein expression (values expressed relative to basal; n = 11–15/group); #P < 0.05 vs. basal. Methods: Western blotting from total lysate of isolated rat ventricular myocytes incubated without (i.e., basal) or with insulin or incremental dose of GGF2. Calsequestrin was used as a loading control. RU, relative units.