(A) Intra-acinar calcium signals were recorded in fura-2–loaded pancreatic acinar cells isolated from control (left) and hM3R transgenic mice. CNO only elicited calcium signaling in acini expressing hM3R. The measurement was repeated in 5 mice each. (B) CNO dose-dependently induced a biphasic amylase secretion in acinar cells from hM3R transgenes (hM3R/BAC). Mean ± SEM (n = 3). Amylase secretion was comparable among CCK-, carbachol-, or CNO-stimulated acinar cells from hM3R/BAC mice (P 0.05). (C) Isolated primary pancreatic acinar cells were stimulated by saline (control), CCK, carbachol, or CNO. Cell membrane damages were manifested as blebbing and increased permeability to ethidium bromide (red). Note CNO caused damages only in pancreatic acini prepared from hM3R/BAC mice. Mean ± SEM (n = 3). Scale bar: 100 μm.