MODELLING OF ELECTRICAL ACTIVITY IN PANCREATIC ISLETS: THE ROLE OF A NOVEL KCa-CHANNEL.
Field:	Other
Authors:	Galvanovskis, Juris Göpel, Sven Rorsman, Patrik
Address of presenting author:	Dept. of Physiology and Neuroscience Sölvegatan 19 223 62 Lund
E-mail:	juris.galvanovskis@mphy.lu.se
Phone:	046 222 0628
Fax:	046 222 7763
Text of abstract:	B-cells, the insulin-secreting cells of pancreas, are electrically coupled through gap junctions and exhibit a synchronised oscillating electrical activity under 10 mM glucose. In order to evaluate conductances contributing to this activity, KATP-, L-type-Ca2+-, KDR, and a new KCa-channel currents were recorded in intact islets. The newly detected KCa-channel in a patched cell was activated with a train of 100 ms long depolarisations ranging from –40 to 0 mV. Kinetic properties of these four channels were evaluated and incorporated into a novel mathematical model of electrical activity in B-cells. Numerical simulations carried out with parameter values found in our experiments showed that the model was capable to recreate the electrical behaviour of B-cells in a set of experimental situations partially listed below. (1) The elevation of glucose in medium surrounding an islet induced depolarisation and action potential firing between –40 and –10 mV. (2) Addition of the novel KCa-current converted continuous spiking into an oscillating electrical activity under 10 mM glucose. (3) Reduction of KCa-current to levels found in single cells resulted in a single-cell-like behaviour. (4) The application of TEA led to a simulated pattern that also agreed well with experimental data. These results suggest that the four conductances found in B-cells within intact islets are sufficient to explain their basic patterns of electrical activity.
Keywords:	Pancreatic islets, electrical activity, modelling

Created 2000-03-15