Fig. 3.
Impact of ambient d-glucose concentration on the ghrelin secretagogic effects of various reagents. Levels of acyl ghrelin released into the culture medium upon 6-h incubation of dispersed mouse gastric mucosal cells in medium (DMEM; 100 U/ml penicillin, 100 μg/ml streptomycin sulfate, and 50 μM octanoate-BSA) containing various concentrations of d-glucose ± 10 μM norepinephrine (NE), 100 nM insulin (Ins), or 10 mM 2-deoxy-d-glucose (2DG) (A), 10 mM l-glucose (B), 0.05% (vol/vol) DMSO, 500 μM tolbutamide (Tolb), or 100 μM diazoxide (DZX) (C), 10 μM NE ± 500 μM Tolb (D), and 100 nM Ins ± 500 μM Tolb (E). In A, the patterned bars in each set represent the ghrelin levels in the medium relative to that observed upon incubation in 1 (636.5 ± 37.0 pg/ml), 5 (444.7 ± 34.8 pg/ml), or 10 mM d-glucose (348.9 ± 10.1 pg/ml) alone (open bars) and are shown as means ± SE for 2 different cell preparations each containing 3 wells. In B, each bar represents the ghrelin level in the medium relative to that observed upon incubation in 1 mM d-glucose (853.8 ± 6.9 pg/ml) and is shown as the mean ± SE for 4 wells. In C, the patterned bars in each set represent the ghrelin levels in the medium relative to that observed upon incubation in 1 (624.2 ± 95.7 pg/ml), 5 (376.3 ± 51.7 pg/ml), or 10 mM d-glucose (313.7 ± 35.2 pg/ml) alone (open bars) and are shown as means ± SE for 2 different cell preparations each containing 2–3 wells. In D and E, each bar represents the ghrelin level in the medium relative to that observed upon incubation in 1 mM d-glucose + 10 μM NE (884.4 ± 63.7 pg/ml) and 1 mM d-glucose + 100 nM Ins (378.0 ± 86.0 pg/ml), respectively, and is shown as the mean ± SE for 2 different cell preparations each containing 2–3 wells. Wells for all these studies contained 1 × 105 cells/well in 500 μl of medium. Asterisks in A denote the level of statistical significance relative to the open bar of the set, and asterisks in B denote the significant effect of the condition noted. *P < 0.05, **P < 0.01, and ***P < 0.001.