Regulation of basal cAMP levels by PDEs in human pancreatic β-cells. Evan P. S. Pratt Kyle E. Harvey Amy E. Salyer Gregory H. Hockerman 10.1371/journal.pone.0215188.g002 https://plos.figshare.com/articles/figure/Regulation_of_basal_cAMP_levels_by_PDEs_in_human_pancreatic_-cells_/9727181 <p>A-C) Subtype-selective PDE inhibitors and IBMX raise cAMP levels in pancreatic β-cells dissociated from human islets under basal conditions (1.7 mM glucose). For each experiment, IBMX (100 μM) and either 8MM-IBMX (100 μM) (A), cilostamide (1 μM) (B) or rolipram (10 μM) (C) were perfused onto the cell. Pancreatic β-cells were identified at the end of each experiment by addition of GLP-1 (50 nM) with and without the α2-receptor agonist clonidine (1 μM). Data shown are representative experiments from single human pancreatic β-cells. D) The percent increase in cAMP levels above baseline elicited by PDE inhibitors in human pancreatic β-cells under basal conditions. IBMX, cilostamide and rolipram significantly elevate cAMP levels above baseline. The percent increase in cAMP levels stimulated by 8MM-IBMX and rolipram is significantly less than that of IBMX (***, P < 0.001, *, P < 0.05 compared to baseline; ###, P < 0.001 compared to IBMX; One-way ANOVA, Tukey post-hoc test). Data shown are average ± SE from 15 cells (8MM-IBMX), 7 cells (cilostamide), 9 cells (rolipram) and 33 cells (IBMX), collected from four human islet preparations. One outlier was removed for IBMX and three outliers were removed for rolipram. E) Resting cAMP levels (mTurquoise2/FRET) in β-cells from eight different human donors. Comparison of pooled data from human β-cells (61 total) to resting cAMP levels in INS-1 cells (41 total) revealed a significantly greater resting cAMP level in human β-cells (***, <i>P</i> < 0.001; Student’s unpaired t-test). Individual data points are shown for each cell measured. Lines represent means ± SE.</p> 2019-08-23 17:33:29 PDE 4 activity subtype-selective PDE inhibitors rat insulinoma cell line INS PDE 3 PDE 4 inhibitor rolipram PDE 4 inhibition potentiate glucose-stimulated insulin secretion 18 mM glucose cAMP levels CREB potentiated insulin secretion PDE 1 PDE 3 inhibitor cilostamide 1.7 mM glucose FRET-based cAMP sensor PDE 1 inhibitor 8 MM-IBMX PDE 3 inhibition PDE 4 inhibition potentiated cAMP levels 16.7 mM glucose PDE 1 inhibition