Stimulation of isolated pancreatic islet cells by arginine.
(A) α- and β-cells were distinguished by their response to an epinephrine pulse in 2.8 mM glucose. (B) Arginine stimulation was blocked by nifedipine (10 μM). The solid traces and shaded areas are the means ± SEM, respectively, for the indicated number of cells. These experiments were repeated four times with similar results using different islet preparations derived from 1 or 2 mice. (C and D) Responses of WT and Sur1−/− α- and β-cells to increasing concentrations of arginine at three concentrations of glucose. Each trace is an average of Ca2+ values from 4–10 cells; the experiments were repeated 4 times with similar results using different islet preparations. Islet preparations were from 1 or 2 mice. The pulse lengths are 5 minutes. The 5.6 and 16.7 mM glucose α-cell traces are offset 0.1 and 0.2 units respectively, for clarity.