On the effect of the intracellular calcium-sensitive K+ channel in the bursting pancreatic beta-cell.

Based on the observation that the calcium-activated K+ channel in the pancreatic islet cells can also be activated by the membrane potential, we have formulated a mathematical model for the electrical activity in the pancreatic beta-cell. Our model contains two types of ionic channels, which are active above the subthreshold glucose concentration in the limit-cycle region: a Ca2+-activated, voltage-gated K+ channel and voltage-gated Ca2+ channel. Numerical simulation of the model generates bursts of electrical activity in response to a variation of kCa, the rate constant for sequestration of intracellular calcium ions. The period and duration of the bursts in response to kCa are in good agreement with experiment. The model predicts that a combined spike and burst pattern can be created using only single species of inward and outward currents, the inactivation kinetics (i.e., h) in the inward current is not a necessary condition for the generation of the pattern, and a given pattern or intensity of electrical activity may produce different levels of intracellular Ca2+ depending on the set of certain electrical parameters.