Metformin Inhibits Mouse Islet Insulin Secretion and Alters Intracellular Calcium in a Concentration-Dependent and Duration-Dependent Manner near the Circulating Range

Figure 3

Higher concentrations of metformin induce cell death. (a–d) Images of islets in bright field (top), annexin V fluorescence in green (middle), and PI in red (bottom) for islets exposed to no metformin (a, untreated), 20 μM (b), 200 μM (c), and 1 mM metformin (d). Regions of interest (ROIs) observed in bright field images were drawn around each islet for fluorescence quantification. (e–f) Quantification of fluorescence (Mean +/− SEM) for annexin V (e) and PI (f). , . Islet number for each condition ranged from from two separate trials.

(a)

(b)

(c)

(d)

(e)

(f)