title: Activation of Ca(2+)-dependent K(+) channels contributes to rhythmic firing of action potentials in mouse pancreatic beta cells.
abstract: We have applied the perforated patch whole-cell technique to beta cells within intact pancreatic islets to identify the current underlying the glucose-induced rhythmic firing of action potentials. Trains of depolarizations (to simulate glucose-induced electrical activity) resulted in the gradual (time constant: 2.3 s) development of a small (<0.8 nS) K(+) conductance. The current was dependent on Ca(2+) influx but unaffected by apamin and charybdotoxin, two blockers of Ca(2+)-activated K(+) channels, and was insensitive to tolbutamide (a blocker of ATP-regulated K(+) channels) but partially (>60%) blocked by high (10-20 mM) concentrations of tetraethylammonium. Upon cessation of electrical stimulation, the current deactivated exponentially with a time constant of 6.5 s. This is similar to the interval between two successive bursts of action potentials. We propose that this Ca(2+)-activated K(+) current plays an important role in the generation of oscillatory electrical activity in the beta cell.
authors.affiliation: Department of Physiological Sciences, Division of Molecular and Cellular Physiology, Lund University, SE-223 62 Lund, Sweden.
authors.forename: S O
authors.initials: SO
authors.lastname: Göpel
authors.forename: T
authors.initials: T
authors.lastname: Kanno
authors.forename: S
authors.initials: S
authors.lastname: Barg
authors.forename: L
authors.initials: L
authors.lastname: Eliasson
authors.forename: J
authors.initials: J
authors.lastname: Galvanovskis
authors.forename: E
authors.initials: E
authors.lastname: Renström
authors.forename: P
authors.initials: P
authors.lastname: Rorsman
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D004594:Electrophysiology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000502:physiology*; D054086:KATP Channels; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000819:agonists / Q000378:metabolism / Q000502:physiology*; D024681:Potassium Channels, Calcium-Activated; D024661:Potassium Channels, Inwardly Rectifying; D014044:Tolbutamide / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D007004:Hypoglycemic Agents; D054086:KATP Channels; D051036:Large-Conductance Calcium-Activated Potassium Channels; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D024661:Potassium Channels, Inwardly Rectifying; C092520:uK-ATP-1 potassium channel; D014044:Tolbutamide