Slow voltage inactivation of Ca2+currents and bursting mechanisms for the mouse pancreatic beta-cell
✍ Scribed by Paul Smolen; Joel Keizer
- Publisher
- Springer
- Year
- 1992
- Tongue
- English
- Weight
- 970 KB
- Volume
- 127
- Category
- Article
- ISSN
- 0022-2631
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✦ Synopsis
Recent whole-cell electrophysiological data concerning the properties of the Ca2+ currents in mouse beta-cells are fitted by a two-current model of Ca2+ channel kinetics. When the beta-cell K+ currents are added to this model, only large modifications of the measured Ca2+ currents will reproduce the bursting pattern normally observed in mouse islets. However, when the measured Ca2+ currents are modified only slightly and used in conjunction with a K+ conductance that can be modulated dynamically by ATP concentration, reasonable bursting is obtained. Under these conditions it is the K-ATP conductance, rather than the slow voltage inactivation of the Ca2+ current, that determines the interburst interval. We find that this latter model can be reconciled with experiments that limit the possible periodic variation of the K-ATP conductance and with recent observations of intracellular Ca2+ bursting in islets.