Forskolin-induced [Ca²⁺]_i oscillations without δ-cell electrical activity. Forskolin induces spontaneous [Ca²⁺]_i spikes sensitive to thapsigargin. (A) Membrane potential (V_m, middle) and changes in [Ca²⁺]_i (ΔF/F₀; bottom) measured simultaneously from an SST-GCaMP3 δ-cell in the absence and presence of 10 µM forskolin. Representative of five independent experiments from three animals. Addition of forskolin is indicted by the horizontal bar. (B) As in A, but in δ-cells pretreated with thapsigargin (10 µM) for >1 h. Representative of three independent experiments from three animals. All experiments were conducted using the perforated patch whole-cell technique.