Figure 2. The excitatory action of insulin on spontaneous MC firing disappears in the presence of K⁺ channel blockers.

A, distance between the ISI distributions (with and without insulin) recorded in the presence of K⁺ channel blockers (4 mm 4-AP and 25 mm TEA). Discharge of a cell was considered to be modulated by insulin when >0.1 and ***P < 0.001 (Kolmogorov–Smirnov test); n.s., not significant. B, distribution of the effect of insulin on the MC population tested in the control condition (CTR) is different from that observed in the presence of K⁺ channel blockers (**P = 0.00026, Fisher's exact test). Indeed, no cell was excited in the presence of K⁺ channel blockers, compared with 62.5% excited cells in the control condition (n = 15/24 with positive D; Fig. 1B).