Modulation of the Bursting Properties of Single Mouse Pancreatic β-Cells by Artificial Conductances

AbstractGlucose triggers bursting activity in pancreatic islets, which mediates the Ca2+ uptake that triggers insulin secretion. Aside from the channel mechanism responsible for bursting, which remains unsettled, it is not clear whether bursting is an endogenous property of individual β-cells or requires an electrically coupled islet. While many workers report stochastic firing or quasibursting in single cells, a few reports describe single-cell bursts much longer (minutes) than those of islets (15–60s). We studied the behavior of single cells systematically to help resolve this issue. Perforated patch recordings were made from single mouse β-cells or hamster insulinoma tumor cells in current clamp at 30–35°C, using standard K+-rich pipette solution and external solutions containing 11.1mM glucose. Dynamic clamp was used to apply artificial KATP and Ca2+ channel conductances to cells in current clamp to assess the role of Ca2+ and KATP channels in single cell firing. The electrical activity we observed in mouse β-cells was heterogeneous, with three basic patterns encountered: 1) repetitive fast spiking; 2) fast spikes superimposed on brief (