Figure 3. Identification of glucagon- and somatostatin-containing cells.

A, fluorescence changes due to a change from 3 to 11 mM glucose from cells depicted in the left panel of B. Note that [Ca²⁺]_i oscillations are abolished due to the presence of high glucose levels. B, left panel: picture of the two cells described in A loaded with the calcium indicator fluo-3. Blue indicates low and red high fluorescence levels. Right panel: identification of cells 1 and 2 as glucagon-containing α-cells by immunofluorescence, shown in green. The result is representative of 5 glucose-responsive cells unambiguously identified from 3 islets. Scale bar represents 15 μm. C, fluorescence signals due to a change from 3 to 11 mM glucose in the cell depicted in the left panel of D. No appreciable change in the frequency of [Ca²⁺]_i oscillations was observed. D, left panel: pseudo-colour picture of the cell described in C within an islet of Langerhans. Right panel, identification of this cell as a somatostatin-containing δ-cell, labelled in green (4 glucose-responsive cells from 2 islets were unambiguously identified). Scale bar represents 15 μm.