Figure 2

Intracellular [Ca²⁺] in adult islets is glucose‐sensitive. (A, left) Islets were imaged in microchambers (~4 μL) cored out of agar, on the bottom of a petri dish. Flow of bulk solution into and out of the dish (~1 mL) was controlled as indicated. (right) GCaMP fluorescence and anti‐insulin staining in representative islet, together with overlay (GCamp fluorescence green, anti‐insulin red). (B) Individual frames of islets at low (2 mmol/L) and high (20 mmol/L) glucose (middle), and in 20 mmol/L glucose plus 30 mmol/L KCl (right). (C) Representative fluorescence traces from individual islets, normalized to initial fluorescence (relative fluorescence units, RFU), during transitions from low glucose to 20 mmol/L d‐ or l‐glucose, and 20 mmol/L glucose plus 30 mmol/L KCl, in absence or presence of diazoxide, as indicated. (D) Summary of calcium responses to high 2 or 20 mmol/L d‐ or l‐glucose, or 20 glucose plus 30 mmol/L KCl, in absence or presence of diazoxide, as indicated from experiments as in C (N = 6–10 in each case). (**) P < 0.05.