Patch-clamp characterisation of somatostatin-secreting -cells in intact mouse pancreatic islets.

Journal article

The perforated patch whole-cell configuration of the patch-clamp technique was applied to superficial cells in intact mouse pancreatic islets. Three types of electrical activity were observed corresponding to alpha-, beta- and delta-cells. The delta-cells were electrically active in the presence of glucose but lacked the oscillatory pattern seen in the beta-cells. By contrast, the alpha-cells were electrically silent at high glucose concentrations but action potentials could be elicited by removal of the sugar. Both alpha- and beta-cells contained transient voltage-activated K+ currents. In the delta-cells, the K+ currents activated above -20 mV and were completely blocked by TEA (20 mM). The alpha-cells differed from the delta-cells in possessing a TEA-resistant K+ current activating already at -40 mV. Immunocytochemistry revealed the presence of Kv3.4 channels in delta-cells and TEA-resistant Kv4.3 channels in alpha-cells. Thus the presence of a transient TEA-resistant current can be used to functionally separate the delta- and alpha-cells. A TTX-sensitive Na+ current developed in delta-cells during depolarisations beyond -30 mV and reached a peak amplitude of 350 pA. Steady-state inactivation of this current was half-maximal at -28 mV. The delta-cells were also equipped with a sustained Ca2+ current that activated above -30 mV and reached a peak of 60 pA when measured at 2.6 mM extracellular Ca2+. A tolbutamide-sensitive KATP channel conductance was observed in delta-cells exposed to glucose-free medium. Addition of tolbutamide (0.1 mM) depolarised the delta-cell and evoked electrical activity. We propose that the KATP channels in delta-cells serve the same function as in the beta-cell and couple an elevation of the blood glucose concentration to stimulation of hormone release.

Authors: Göpel, S; Kanno, T; Barg, S; Rorsman, P

• Publication status: Published
• Journal: Journal of physiology
• Volume: 528
• Issue: Pt 3
• Pages: 497-507
• Publication date: 2000-11-01
• DOI: 10.1111/j.1469-7793.2000.00497.x
• EISSN: 1469-7793
• ISSN: 0022-3751
• Language: English
• Keywords: Potassium Channels; Mice, Inbred Strains; Electric Conductivity; Mice; Islets of Langerhans; Sodium Channels; Shal Potassium Channels; Patch-Clamp Techniques; Ion Channel Gating; Somatostatin-Secreting Cells; Homeostasis; Potassium Channels, Voltage-Gated; Adenosine Triphosphate; Animals; Electrophysiology; Shaw Potassium Channels; Somatostatin