FIGURE 1.

GLP‐1 receptor antagonism inhibits both GLP‐1‐ and glucagon‐stimulated [cAMP]_pm increases in β‐cells. A‐C, [cAMP]_pm recordings from a single MIN6 β‐cell (A, representative for 26 cells from four experiments), and single mouse (B, 36 cells from eight experiments) and human (C, representative for 20 cells from five experiments with islets from two donors) β‐cells within intact islets, showing that ex‐9 prevents the [cAMP]_pm elevation induced by 10 nmol/L GLP‐1. The [cAMP]_pm‐lowering effect of 10 µmol/L adrenaline (adr) is used to verify the identity of the islet β‐cells. D‐F, Similar [cAMP]_pm recordings from single MIN6 (D, representative for 25 cells from four experiments), mouse (E, representative for 20 cells from six experiments) and human (F, representative for 14 cells from 6 experiments with islets from three donors) β‐cells showing that ex‐9 prevents [cAMP]_pm elevations induced by 10 nmol/L glucagon. G, Recording from a MIN6 β‐cell showing that ex‐9 reduces basal [cAMP]_pm and prevents the GLP‐1‐induced elevation. Representative for 23 cells from four experiments. H, I, Box plots of the magnitudes of the [cAMP]_pm reductions induced by ex‐9 in cells stimulated with GLP‐1 (H) or glucagon (I). P values are given for comparisons of mean values with Student's paired t test